Semiconductor device

ABSTRACT

As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the “Lead-On-Chip” or “Chip-On-Lead” structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional application of Ser. No.08/646,031, filed May 7, 1996, which is a continuation application ofSer. No. 08/293,555, filed Aug. 22, 1994, which is a divisionalapplication of Ser. No. 07/990,272, filed Dec. 14, 1992, which is adivisional application of Ser. No. 07/915,861, filed Jul. 20, 1992,which is a continuation application of Ser. No. 07/690,551, filed Apr.24, 1991, which is a continuation application of Ser. No. 07/409,332,filed Sep. 19, 1989 (now U.S. Pat. No. 5,068,712), the contents of eachof which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a semiconductor device and, moreparticularly, to a technology effective if applied to the package of alarge-scale integrated circuit of high integration.

[0003] In the prior art, the semiconductor chip is sealed up with amolding resin so that it may be protected. Several methods are used tomount leads in position on the semiconductor chip before the sealing.

[0004] For example, a lead frame having tabs at its center is used andmounted before the semiconductor chip is sealed. In this prior art,there is known a method of connecting electrode pads around thesemiconductor chip with the corresponding inner leads through bondingwires.

[0005] The common problem among the semiconductor packages of the priorart is that the metal lead frame is cracked along the mold parting linesproviding the exits of the lead lines.

[0006] Another problem is that the passages for moisture or contaminantsin the atmosphere to steal along the metal lead wires from the outsideinto the semiconductor chip are relatively short.

[0007] Moreover, the surface mounting type package is seriously troubledby the so-called “reflow cracking” problem that the moisture containedin the package is expanded by the heat of the solder reflow to crack thepackage.

[0008] Still another problem is that the bonding wires necessary forconnecting the inner leads with the electrode pads of the semiconductorchip cannot be intersected partly because they are relatively long andpartly because they are alternately assigned to input/output terminals.

[0009] In order to solve the above-specified problems, therefore, therehas been proposed in Japanese Patent Laid-Open No. 241959/1986(corresponding to E.P. Publication No. 0198194) a semiconductor devicein which a plurality of inner leads are adhered to the circuit formingsurface of a semiconductor chip through the semiconductor chip andinsulating films by an adhesive, in which the inner leads and thesemiconductor chip are electrically connected through bonding wires andin which common inner leads (or bus bar inner leads) are disposed in thevicinity of the longitudinal center line of the circuit forming surfaceof the semiconductor chip.

[0010] Also disclosed in Japanese Patent Laid-Open No. 167454/1985 or218139/1986 (corresponding to U.S. Ser. No. 845,332) is the packagestructure of the so-called “tabless lead frame type”, in which the tabs(i.e., the die pads) mounting the chip are eliminated to mount the chipon the insulating films adhered to the leads (i.e., Chip On Lead) and inwhich the bonding pads of the chip and the leading ends of the leads areconnected through wires.

[0011] Also proposed in Japanese Patent Laid-Open No. 92556/1984 or236130/1986 is the package structure in which the leads are adhered tothe upper surface of the chip (i.e., Lead On Chip) by an adhesive and inwhich the bonding pads of the chip and the leading end portions of theleads are connected through wires.

[0012] According to the above-specified package structure arranged withthe leads on the upper or lower surface of the chip, the heat andmoisture resistances of the package can be improved because the leads inthe package can be elongated. Thanks to the elimination of the tabs,moreover, the contact between the resin and the leads is improved toimprove the reflow cracking resistance. As a result, even thelarge-sized chip can be packed in the package of the existing size.Moreover, this package structure is advantageous in reducing the wiringdelay because it can shorten the bonding wires.

SUMMARY OF THE INVENTION

[0013] We have investigated the aforementioned semiconductor devices ofthe prior art and have found the following problems:

[0014] (1) In the semiconductor device of the prior art, the inner leadsare adhered to the circuit forming surface of the semiconductor chipthrough the semiconductor chip and the insulating films by the adhesive.Because of the large stray capacity between the inner leads and thesemiconductor chip, the semiconductor device has a problem that thesignal transmission rate is dropped by the large stray capacity toincrease the electrical noises.

[0015] (2) Because of the large area of the insulating films, the amountof moisture absorbed is increased so that the absorbed moisture isgasified and expanded in the package during the reflow, thus causing aproblem that the package cracking is established by the moistureexpansion.

[0016] (3) Since the aforementioned insulating films are made of a resinof polyimide, the amount of absorbed moisture is increased so that theabsorbed moisture is gasified and expanded in the package during thereflow, thus causing the problem of package cracking.

[0017] (4) Since the aforementioned adhesive as made of an acrylicresin, it is degraded by the pressure cracker test or the like, thusraising a problem that the reliability is dropped by the electricalleakage between the leads and the corrosions of the aluminum electrodes.

[0018] (5) Since the circuit forming surface of the semiconductor chipis not coated all over with the resin coating of polyimide forprotections against alpha rays, there arises a problem that errors arecaused by the alpha rays.

[0019] (6) The common inner leads (i.e., bus bar inner leads) are usedas radiating plates, but the element having a large exothermic portionis not covered all over with the inner leads. There arises a problemthat the radiation is insufficient in an element of 1 watt or higher.

[0020] (7) Since the insulating films made of the aforementioned resinof polyimide has a large area, there arises a problem that thesemiconductor device is weak in the temperature cycle.

[0021] (8) The wire bonding is accomplished across the aforementionedinner leads (i.e., bus bar inner leads), thus raising a problem in poorproductivity.

[0022] (9) The aforementioned adhesive layer is so soft that the wirebonding conditions are difficult to set, thus raising the problem ofpoor productivity.

[0023] (10) This problem of poor productivity is also caused by the poorworkability for mounting the insulating films on the semiconductor chip.

[0024] (11) Since the semiconductor chip is insufficiently fixed by theportions of the inner leads, it is moved in the resin sealing (ormolding) operation, thus raising a problem that the productivity ispoor.

[0025] An object of the present invention is to provide a technique forimproving the reliability of a semiconductor device.

[0026] An object of the present invention is to provide a technique fora semiconductor device to improve the signal transmission rate due tothe stray capacity between the semiconductor chip and the leads and toreduce the electrical noises.

[0027] Another object of the present invention is to provide a techniquefor a semiconductor device to improve the radiating efficiency of theheat generated.

[0028] Another object of the present invention is to provide a techniquefor a semiconductor device to reduce the influences of the heat duringthe reflow.

[0029] Another object of the present invention is to provide a techniquefor a semiconductor device to reduce the influences of the heat in thetemperature cycle.

[0030] Another object of the present invention is to provide a techniquefor a semiconductor device to prevent the molding defects from beingcaused.

[0031] Another object of the present invention is to provide a techniquefor a semiconductor device, which has a package structure arranged withleads on the upper or lower surface of the chip, to reduce the parasiticcapacity to be established between the chip and the leads.

[0032] Another object of the present invention is to provide a techniquefor a semiconductor device to improve the productivity.

[0033] Another object of the present invention is to provide a techniqueto improve the moisture resistance.

[0034] The foregoing and other objects and novel features of the presentinvention will become apparent from the following description to be madewith reference to the accompanying drawings.

[0035] Representatives of the invention to be disclosed herein will bebriefly described in the following:

[0036] 1. A semiconductor device of the type, in which common innerleads are adhered to the vicinity of the center line taken in the X- orY-direction of the principal surface of a semiconductor chip throughinsulators for insulating the semiconductor chip electrically, in whicha plurality of signal inner leads are adhered to the principal surfaceof the semiconductor chip through insulators for insulating thesemiconductor chip electrically, and in which the inner leads, thecommon inner leads and the semiconductor chip are electrically connectedthrough bonding wires and sealed up with a mold resin, wherein theimprovement resides in that the gaps between the semiconductor chip atthe outer lead side than the portions bonded to the insulators and saidinner leads are wider than those from the portions bonded to theinsulators.

[0037] 2. A semiconductor device according to the foregoing item 1,wherein the area occupied by the insulators is at most one half of thearea of the semiconductor chip.

[0038] 3. A semiconductor device according to the foregoing item 1,wherein the area for bonding the insulators and the principal surface ofthe semiconductor chip is practically minimized.

[0039] 4. A semiconductor device according to each of the foregoingitems 1 to 3, wherein the insulators are molded of a resin containing aportion of the inner leads.

[0040] 5. A semiconductor device according to each of the foregoingitems 1 to 4, wherein the material of the insulators satisfies at leasttwo of the following conditions:

[0041] (1) The saturated moisture absorption is equal to or less thanthat of the sealing resin;

[0042] (2) The dielectric constant is 4.0 or less for 10³ Hz at atemperature from the room temperature to 200° C.;

[0043] (3) The Barcol hardness (GYZ J934-1) at 200° C. is 20 or more;

[0044] (4) The amount of a soluble halogen element is 10 ppm or less inthe case of the uranium and thorium contents of 1 ppb or less and in thecase of extraction at 120° C. for 100 hours;

[0045] (5) The contact between the semiconductor chip and the innerleads is excellent;

[0046] (6) The thermal expansion coefficient is 20×10⁻⁶/° C. or less;and

[0047] (7) The theremost resin has a glass transition temperature of220° C. or more.

[0048] 6. A semiconductor device of the type, in which all of aplurality of inner leads are so arranged on the principal surface of asemiconductor chip as to float from the principal surface of thesemiconductor chip, in which the semiconductor chip is adhered and fixedto the deenergized ones of the inner leads, and in which the remaininginner leads and the semiconductor chip are electrically connectedthrough bonding wires and sealed up with a mold resin.

[0049] 7. A semiconductor device of the type, in which a plurality ofinner leads are so arranged on the principal surface of a semiconductorchip as to flat from the principal surface of the semiconductor chip, inwhich the side of the semiconductor chip opposite to the principalsurface is adhered and fixed through insulators by a portion of theinner leads, and in which the inner leads and the semiconductor chip areelectrically connected through bonding wires and sealed up with a moldresin.

[0050] 8. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipthrough insulators for insulating the semiconductor chip electrically,and in which the inner leads and the semiconductor chip are electricallyconnected through bonding wires, wherein the improvement resides: inthat radiating leads electrically insulated from the semiconductor chiphave their one-side ends held on the principal surface of thesemiconductor chip at the central portion of the longitudinal side ofthe package; and in that the other terminals of the radiating leads areextended to above the principal surface of the semiconductor chipoutside the package.

[0051] 9. A semiconductor device according to the foregoing item 8,wherein the other ends of the radiating leads are extended to below theside opposite to the principal surface of the semiconductor chip outsideof the package.

[0052] 10. A semiconductor device according to the foregoing item 8 or9, wherein the one-side ends of the radiating leads are extended toabove the exothermic portions of the principal surface of thesemiconductor chip.

[0053] 11. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipthrough insulators for insulating the semiconductor chip electrically,and in which the inner leads and the semiconductor chip are electricallyconnected through bonding wires, wherein the improvement resides: inthat one-side ends of radiating leads electrically insulated from thesemiconductor chip are held on the central portion of the longitudinalside of the package and on the side opposite to the principal surface ofthe semiconductor chip; and in that the other ends of the radiatingleads are extended to above the principal surface of the semiconductorchip outside of the package or to below the side opposite to theprincipal surface of the semiconductor chip outside of the package.

[0054] 12. A semiconductor device according to any of the foregoingitems 8 to 11, wherein the radiating leads are equipped at their outsidewith radiating plates.

[0055] 13. A semiconductor device according to any of the foregoingitems 6 to 12, wherein common inner leads are arranged in the vicinityof the X- or Y-directional center line of the principal surface of thesemiconductor chip.

[0056] 14. A semiconductor device according to any of the foregoingitems 1 to 12, wherein the bonding wires are coated with insulators.

[0057] 15. A semiconductor device according to any of the foregoingitems 1 to 6 or 13, wherein the semiconductor chip has its principalsurface arranged with bonding pads which do not intersect with thebonding wires arranged on the principal surface and the common innerleads.

[0058] 16. A semiconductor device according to any of the foregoingitems 1 to 15, wherein the mold resin material is a resin compositewhich is prepared by blending a thermoset resin with 70 wt % or more ofa substantially spherical inorganic filler having a particle sizedistribution of 0.1 to 100 microns, an average particle diameter of 5 to20 microns and the maximum packing density of 0.8 or more.

[0059] 17. A semiconductor device according to the foregoing item 16,wherein the mold resin material is composed mainly of at least one of aphenol-set type epoxy resin, a resol type phenol resin and abismaleimide resin.

[0060] 18. A semiconductor device according to the foregoing item 16 or17, wherein the mold resin material is composed mainly of the resol typephenol resin or the bismaleimide resin as the thermoset resin, andwherein its molding has a bending strength of 3 kgf/mm² or more at 215°C.

[0061] 19. A semiconductor device according to any of the foregoingitems 16 to 18, wherein the mold resin material contains as itsinorganic filler spherical molten silica having a particle sizedistribution of 0.1 to 100 microns, an average particle diameter of 5 to20 microns and the maximum packing density of 0.8 or more.

[0062] 20. A semiconductor device according to any of the foregoingitems 16 to 19, wherein the mold resin material is blended as itsinorganic filler with 67.5 vol % or more of substantially sphericalmolten silica having a particle size distribution of 0.1 to 100 microns,an average particle diameter of 5 to 20 microns and the maximum packingdensity of 0.8 or more, and wherein its molding has a linear expansioncoefficient of 1.4×10⁻⁵/° C. or less.

[0063] 21. A semiconductor device according to any of the foregoingitems 16 to 20, wherein the mold resin material has an extract of pH 3to 7, in case at is mixed with ion exchange water in an amount of tentimes and extracted at 120° C. for 100 hours, an electric conductivityof 200 μS/cm or less, and extractions of halogen ions, ammonia ions andmetal ions of 10 ppm or less.

[0064] 22. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that the adhesive is blended as a filler withspherical fine particles which have a constant particle diameter andwhich are selected from a thermoplastic resin or thermoset resin havinga softening temperature higher than the inorganic or adheringtemperature.

[0065] 23. A semiconductor device of the type, according to theforegoing items 1 to 22 in which a plurality of inner leads are eitheradhered to the principal surface of a semiconductor chip with anadhesive through insulators for insulating the semiconductor chipelectrically or arranged in a state floating from the principal surfaceof the semiconductor chip, and in which the inner leads and thesemiconductor chip are electrically connected through bonding wires,wherein the improvement resides: in that the semiconductor chip iscoated with an alpha ray shielding polyimide film at all its circuitforming region other than bonding pads; and in that the semiconductorchip is formed with an insulating film on its portion to which areadhered at least the leading ends of the inner leads or suspensionleads.

[0066] 24. A semiconductor device according to the foregoing item 23,wherein the insulators are made of a thermoset resin containing aprintable inorganic filler.

[0067] 25. A semiconductor device according to the foregoing item 23 or24, wherein the area occupied by the insulators is at most one half ofthe chip area.

[0068] 26. A semiconductor device according to any of the foregoingitems 23 to 25, wherein the semiconductor chip is formed with apolyimide film at its side opposite to the principal surface.

[0069] 27. A semiconductor device according to any of the foregoingitems 23 to 26, wherein the insulators are formed highly accurately by awafer process including the steps of: a solvent-peeling type dry film toa semiconductor wafer; exposing and developing the dry film in anordinary manner; applying a pasty insulator and burying it withsqueezee; heating to cure the film; and peeling the film.

[0070] 28. A semiconductor device according to the foregoing item 26,wherein the wafer process further includes the step of forming theinsulators by developing and exposing a solder resist dry film.

[0071] 29. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that an insulating film is arranged on all orsome of the inner leads opposed and closest to the semiconductor chip.

[0072] 30. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip has its principalsurface covered wholly or partially with a substance which is moreflexible or fluid than the mold resin to cover some or all of thebonding wires while the outside being sealed up with a resin.

[0073] 31. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip has its principalsurface covered wholly or partially with a bonding resin which coverssome or all the bonding wires while the outside being sealed up with themold resin.

[0074] 32. A semiconductor device according to the foregoing item 31,wherein the outer surface of the mold resin covering the side of thesemiconductor chip other than the main surface is recessed to expose aportion of the semiconductor chip substantially to the outside.

[0075] 33. A semiconductor device according to any of the foregoingitems 30 to 32, wherein common inner leads are disposed in the vicinityof the X- or Y-directional center line of the principal surface of thesemiconductor chip.

[0076] 34. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip is formed with arecess or rise in its side other than the principal surface.

[0077] 35. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip is formed with aplurality of grooves in its side other than the principal surface.

[0078] 36. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip is formed with arecess, a rise or a plurality of grooves in its side other than theprincipal surface while being left with a silicon oxide film.

[0079] 37. A semiconductor device of the type, in which a plurality ofinner leads are adhered to the principal surface of a semiconductor chipwith an adhesive through insulators for insulating the semiconductorchip electrically, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides in that the distance from the portions of the innerleads contacting with the semiconductor chip to the outer wall of apackage is made larger than the distance from the side of thesemiconductor chip opposite to the principal surface to the outer wallof the package.

[0080] 38. A semiconductor device according to any of the foregoingitems 1 to 37, wherein the semiconductor chip is two in which thebonding pads to the inner leads are disposed in mirror symmetry, andwherein the inner leads and the bonding pads of the semiconductor chipare electrically connected across the inner leads at the side of theprincipal surface of the two semiconductor chips and are sealed up witha mold resin.

[0081] 39. A semiconductor device according to any of the foregoingitems 34 to 38, wherein common inner leads are arranged in the vicinityof the X- or Y-directional center line of the semiconductor chips.

[0082] 40. A semiconductor device according to any of the foregoingitems 1 to 39, wherein the surface opposed to a substrate mounting saidsemiconductor device is formed with at least one of radiating groovewhich has its two ends opened to the outside at the sides of thesemiconductor device.

[0083] 41. A semiconductor device according to the foregoing item 40,wherein the side of the semiconductor device opposite to the side formedwith the radiating groove is formed with a second radiating groove whichis extended in the same direction of the first-named radiating grooveand which has its two ends opened to the outside of the sides of thesemiconductor device.

[0084] 42. A semiconductor device according to the foregoing item 41 or42, wherein the mold resin in the bottom of the radiating grooves formedin the surface opposed to the substrate mounting the semiconductordevice has a thickness of 0.3 mm or less.

[0085] 43. A semiconductor device according to any of the foregoingitems 40 to 42, wherein common inner leads are arranged in the vicinityof the X- or Y-directional center line of the principal surface of thesemiconductor chip.

[0086] 44. A semiconductor device according to any of the foregoingitems 40 to 43, wherein the semiconductor devices are so packed in theirmounting substrates that their radiating grooves merge into each other.

[0087] 45. A semiconductor device wherein leads arranged in the upper orlower surface of a chip packed in a package are partially folded outwardwith respect to the upper or lower surface of the chip.

[0088] According to the means of the foregoing item 1, the inner leadsare so stepped that the gaps between the semiconductor chip at the outerlead side than the portions bonded to the insulators and said innerleads are wider than those from the portions bonded to the insulators.The stray capacity between the semiconductor chip and the leads can bemade lower than that of the prior art to improve the signal transmissionrate and reduce the electrical noises.

[0089] According to the means of the foregoing item 2, the area of theprincipal surface of the semiconductor chip occupied by the insulatorsis at most one half of the area of the semiconductor chip so that themoisture absorption by the insulating films can be dropped to reduce theinfluences of the heat during the reflow and in the temperature cycle.

[0090] Since, moreover, the stray capacity between the semiconductorchip and the leads is lower than that of the prior art, it is possibleto improve the signal transmission rate and to reduce the electricalnoises.

[0091] According to the means of the foregoing item 3, the area forbonding the insulators and the principal surface of the semiconductorchip is practically minimized to minimize the moisture absorption by theinsulating films. As a result, it is possible to reduce the influencesof the heat during the reflow and in the temperature cycle. Since,moreover, the stray capacity between the semiconductor chip and theleads is lower than that of the prior art, it is possible to improve thesignal transmission rate and to reduce the electrical noises.

[0092] According to the means of the foregoing item 4, the insulators onthe principal surface of the semiconductor chip are made of the resinmolding including a portion of the inner leads to sufficiently enlargethe distance between the semiconductor chip and the inner leads so thatthe stray capacity between the semiconductor chip and the leads is farlower than that of the prior art. As a result, it is possible to improvethe signal transmission rate and to reduce the electrical noises.

[0093] Since, moreover, the molding resin is selected as a materialhaving a good matching with the sealing resin, it is possible to preventthe peeling between the molding resin and the sealing resin (or moldresin). As a result, it is possible to reduce the leakage between theinner leads.

[0094] According to the means of the foregoing item 5, the optimuminsulator can be selected by the semiconductor element.

[0095] According to the means of the foregoing item 6, the semiconductorchip is adhered and fixed to those of the inner leads, which are notenergized, whereas the remaining inner leads are arranged apart (i.e.,electrically insulated) therefrom on the principal surface of thesemiconductor chip. Since no insulating film is use, the moistureresistance can be improved. Moreover, the step of adhering theinsulating film is eliminated.

[0096] According to the means of the foregoing item 7, the plural innerleads are arranged apart (or electrically insulated) from principalsurface of a semiconductor chip, and the side of the semiconductor chipopposite to the principal surface is adhered and fixed throughinsulators by a portion of the inner leads, and in which the inner leadsand the semiconductor chip are electrically connected through bondingwires and sealed up with a mold resin. Since the inner leads are notadhered to the principal surface of the semiconductor chip, thisprincipal surface can be prevented from being broken or damaged. Since,moreover, no insulating film is used on the principal surface of thesemiconductor chip, it is possible to improve the moisture resistance.

[0097] According to the means of the foregoing item 8, radiating leadselectrically insulated from the semiconductor chip have their one-sideends held at the central portion of the longitudinal side of thepackage, and the other terminals of the radiating leads are extended toabove the principal surface of the semiconductor chip outside thepackage. As a result, it is possible to improve the radiating efficiencyof the heat of the exothermic portions of the semiconductor chip.

[0098] According to the means of the foregoing item 9, the other ends ofthe radiating leads of the means of the item 9 are extended to below theside opposite to the principal surface of the semiconductor chip outsideof the package. As a result, it is possible to improve the radiatingefficiency of the heat of the exothermic portions of the semiconductorchip.

[0099] According to the means of the foregoing item 10, the one-sideends of the radiating leads of the means of the foregoing item 9 areextended to above the exothermic portions of the principal surface ofthe semiconductor chip. As a result, it is possible to improve theradiating efficiency of the heat of the exothermic portions of thesemiconductor chip.

[0100] According to the means of the foregoing item 11, one-side ends ofradiating leads electrically insulated from the semiconductor chip ofthe means of the foregoing item 10 are held on the central portion ofthe longitudinal side of the package and on the side opposite to theprincipal surface of the semiconductor chip, and the other ends of theradiating leads are extended to above the principal surface of thesemiconductor chip outside of the package or to below the side oppositeto the principal surface of the semiconductor chip outside of thepackage. As a result, it is possible to improve the radiating efficiencyof the heat of the exothermic portions of the semiconductor chip.

[0101] According to the means of the foregoing item 12, the radiatingleads of the means of any of the foregoing items 8 to 11 are equipped attheir outside with radiating plates. As a result, it is possible tofurther improve the radiating efficiency of the heat of the exothermicportions of the semiconductor chip.

[0102] According to the means of the foregoing item 13, common innerleads (i.e., bus bar inner leads) of the means of any of the foregoingitems 1 to 12 are arranged in the vicinity of the X- or Y-directionalcenter line of the principal surface of the semiconductor chip. As aresult, the bonding wires of the reference voltage (V_(SS)) or the powersource voltage (V_(CC)) in the semiconductor chip can be wired within asmall area without any shorting. It is also possible to improve theworkability of the wire bonding.

[0103] According to the means of the foregoing item 14, the bondingwires of the means of the foregoing item 13 are coated with insulators.As a result, the bonding wires for connecting the signal line innerleads and the semiconductor chip can be prevented from being shortedwith the signal inner leads.

[0104] According to the means of the foregoing item 15, thesemiconductor chip of the means of the foregoing item 14 has itsprincipal surface arranged with bonding pads (i.e., external terminals)which do not intersect with the bonding wires arranged on the principalsurface and the common inner leads (i.e., bus bar inner leads). As aresult, the bonding wires for connecting the signal line inner leads andthe semiconductor chip can be prevented from being shorted with thesignal inner leads.

[0105] According to the means of the foregoing items 16 to 21:

[0106] (1) The sealing material using as a filler the substantiallyspherical molten silica having a particle size distribution of 0.1 to100 microns, an average diameter of 5 to 20 microns and the maximumpacking density of 0.8 or more has a lower molten viscosity and a highermaterial fluidicity than the angular molten silica in current use. Whenin the molding operation, the gold (Au) wires or leads are neitherdeformed nor is flown away the semiconductor chip. It is also possibleto pack the narrow gap of the package fully.

[0107] (2) Since the sealing material using the spherical molten silicais little influenced in its molten viscosity and fluidicity, it ispossible to increase the loading thereby to reduce the thermal expansionof the material.

[0108] (3) An excellent reliablity can be attained if the resol typephenol resin and polyimide resin used are highly pure.

[0109] (4) The sealing material using the highly pure resol type phenolresin and polyimide resin provides moldings of high heat resistance andexcellent mechanical strength at a high temperature. As a result, it ispossible to attain both a reflow resistance (to package cracking) incase the package absorbs moisture and a reliability in the moistureresistance and the resistance to thermal shocks after the reflow.

[0110] According to the means of the foregoing item 22, a filler ofspherical fine particles having a constant particle diameter is blendedin the adhesive of the means of each of the foregoing items 1 to 21. Asa result, the gap between the semiconductor chip and the leads can becontrolled to a constant value (equal to the filler diameter) so thatthe dispersion of the capacity between the semiconductor chip and theleads can be reduced.

[0111] According to the means of the foregoing item 23, thesemiconductor chip of the means of each of the foregoing items 1 to 21is coated with an alpha ray shielding polyimide film at all its circuitforming region other than bonding pads, and the semiconductor chip isformed with an insulating film on its portions to which are adhered atleast the leading ends of the inner leads or suspension leads. As aresult, the whole circuit forming region can be shielded from the alpharays by the alpha ray shielding polyimide film, and the semiconductorchip can be adhered and fixed by the insulating film.

[0112] Since, moreover, the insulating film is formed on thesemiconductor chip at only the portions to which are adhered at leastthe leading ends of the inner leads and the suspension leads, it ispossible to reduce the stray capacity between the semiconductor chip andthe inner leads.

[0113] Incidentally, the wafer is not warped even if the thickinsulators are formed by the wafer process but partially.

[0114] According to the means of the foregoing item 24, the insulatingfilms of the means of the foregoing item 23 are made of a thermosetresin containing a printable inorganic filler. As a result, theinsulating films can be made highly accurate in the wafer process.

[0115] According to the means of the foregoing item 25, the areaoccupied by the insulating films of the foregoing item 23 or 24 is atmost one half of the chip area. As a result, the moisture absorption bythe insulating films can be dropped to reduce the influences of the heatduring the reflow and the in the temperature cycle.

[0116] Since, moreover, the stray capacity between the semiconductorchip and leads can be made smaller than that of the prior art, it ispossible to improve the signal transmission rate and to reduce theelectrical noises.

[0117] According to the means of the foregoing item 26, thesemiconductor chip of the means of each of the foregoing items 22 to 24is formed with a polyimide film at its side opposite to the principalsurface. As a result, it is possible to prevent the cracking from beingcaused by the heat of the reflow.

[0118] According to the means of the foregoing item 27, the insulatorsof means of each of the foregoing items 23 to 26 are formed highlyaccurately by a wafer process including the steps of: a solvent-peelingtype dry film to a semiconductor wafer; exposing and developing the dryfilm in an ordinary manner; applying a pasty insulator and burying itwith squeezee; heating to cure the film; and peeling the film. Thus, theinsulators can be formed highly accurately by the batch process toimprove the productivity.

[0119] According to the means of the foregoing item 28, the insulatorsof the means of the foregoing item 26 are formed by developing andexposing a solder resist dry film. As a result, the productivity can beimproved.

[0120] According to the means of the foregoing item 29, the insulatingfilm is formed in a lead frame state on all or some of the inner leadsopposed and closest to the semiconductor chip. As a result, theinsulating film between the semiconductor chip and the inner leads ofthe means of the foregoing item 2 or 3 can be easily provided in animproved productivity.

[0121] According to the means of the foregoing item 30, thesemiconductor chip has its principal surface covered wholly or partiallywith a substance which is more flexible or fluid than the sealing resin(or mold resin) to cover some or all of the bonding wires while theoutside being sealed up with a resin. As a result, the mold resin can bekept away from direct contact with the bonding wires to prevent thebonding wires from being repeatedly deformed by the relativedeformations between the semiconductor chip and the resin in thetemperature cycle and accordingly from being broken due to fatigue.

[0122] According to the means of the foregoing item 31, thesemiconductor chip has its principal surface covered wholly or partiallywith a bonding resin which covers some or all the bonding wires whilethe outside being sealed up with the mold resin. As a result, the moldresin can be kept away from direct contact with the bonding wires toprevent the bonding wires from being repeatedly deformed by the relativedeformations between the semiconductor chip and the resin in thetemperature cycle and accordingly from being broken due to fatigue.

[0123] According to the means of the foregoing item 32, the outersurface of the mold resin covering the side of the semiconductor chip ofthe means of the foregoing item 31 other than the main surface isrecessed to expose a portion of the semiconductor chip substantially tothe outside. The resin cracking during the reflow soldering operationcan be prevented with neither poor moisture resistance of the bondingpads nor wire disconnection in the temperature cycle.

[0124] Here, the word “substantially” imagines that there exists eithersuch a thin cover film of resin as will e inevitably formed on thesurface of a semiconductor chip during the fabrication process or such athin resin layer as will be broken in case a steam pressure is built upin the package.

[0125] According to the means of the foregoing item 33, the common innerleads (or bus bar inner leads) of the means of each of the foregoingitems 30 to 32 are disposed in the vicinity of the X- or Y-directionalcenter line of the principal surface of the semiconductor chip. As aresult, the bonding wires of the reference voltage (V_(SS)) or the powersource voltage (V_(CC)) in the semiconductor chip can be wired within asmall area without any shorting. It is also possible to improve theworkability of the wire bonding.

[0126] According to the means of the foregoing item 34, thesemiconductor chip is formed with a recess or rise in its side otherthan the principal surface. As a result, the mold resin can berestricted by the semiconductor chip to reduce the stress which is to begenerated in the mold resin portion of the corners of the non-circuitsurface of the semiconductor chip to be subjected to the reflowcracking, so that this reflow cracking can be prevented.

[0127] According to the means of the foregoing item 35, thesemiconductor chip is formed with a plurality of grooves in itsnon-circuit surface. As a result, the mold resin can be restricted bythe semiconductor chip to reduce the stress which is to be generated inthe mold resin portion of the corners of the non-circuit surface of thesemiconductor chip to be subjected to the reflow cracking, so that thisreflow cracking can be prevented.

[0128] According to the means of the foregoing item 36, thesemiconductor chip is formed with a recess, a rise or a plurality ofgrooves in its side other than the principal surface while being leftwith a silicon oxide (SiO₂) film. Since the adhesion between the siliconoxide (SiO₂) film and the mold resin is strong, it is possible toprevent the peeling of the mold resin from the side of the semiconductorchip opposite to the circuit forming surface. Thanks to the recess orrise or the plural grooves, moreover, at is possible to reduce thestress which is generated in the mold resin portion of the corner of thenon-circuit side of the semiconductor chip by the mold resin so that thereflow cracking can be prevented.

[0129] According to the means of the foregoing item 37, the distancefrom the portions of the inner leads contacting with the semiconductorchip to the outer wall of a package is made larger than the distancefrom the side of the semiconductor chip opposite to the principalsurface to the outer wall of the package. As a result, the average flowspeeds of the resin through the individual passages can be equalized toprevent the formation of voids and bending and shortage of packing ofthe bonding wires. Since, moreover, the resistances to the resin flowsin the individual passages are equalized, the semiconductor chip and theleads can be prevented from changing to realize the molding of a highlyreliable package.

[0130] According to the means of the foregoing item 38, thesemiconductor chip is two in which the bonding pads to the inner leadsare disposed in mirror symmetry, and wherein the inner leads and thebonding pads of the semiconductor chip are electrically connected acrossthe inner leads at the side of the principal surface of the twosemiconductor chips and are sealed up with a mold resin. As a result, itis possible to package the element having the twice capacity withoutchanging the external shape.

[0131] According to the means of the foregoing item 39, the common innerleads (or bus bar inner leads) are arranged in the vicinity of the X- orY-directional center line of the semiconductor chips of the means ofeach of the foregoing items 34 to 38. As a result, the bonding wires ofthe reference voltage (V_(SS)) or the power source voltage (V_(CC)) inthe semiconductor chip can be wired within a small area without anyshorting. It is also possible to improve the workability of the wirebonding.

[0132] According to the means of any of the foregoing items 40 to 42,the heat transfer surface area of the resin-sealed type semiconductordevice can be enlarged to drop the heat resistance of the semiconductordevice.

[0133] According to the means of the foregoing item 44, thesemiconductor devices of the means of each of the foregoing items 40 to43 are so packed in their mounting substrates that their radiatinggrooves merge into each other. The cooling draft can be established inthe direction of the radiating grooves and the second radiating groovesto cool the individual semiconductor devices efficiently.

[0134] According to the means of the foregoing item 45, the leads arepartially folded outward with respect to the upper (or lower) side ofthe chip so that the distance between the chip and leads can be enlargedto reduce the aforementioned parasitic capacity.

BRIEF DESCRIPTION OF THE DRAWINGS

[0135]FIG. 1 is a partially sectional perspective view showing aresin-sealed type semiconductor device for sealing a DRAM according toEmbodiment I of the present invention;

[0136]FIG. 2 is a top plan view of FIG. 1;

[0137]FIG. 3 is a section taken along line I-I of FIG. 2;

[0138]FIG. 4 is a layout showing the schematic structure of the DRAMshown in FIG. 1;

[0139]FIG. 5 is an overall top plan view showing the lead frame shown inFIG. 1;

[0140]FIGS. 6 and 7 are sections showing essential portions showing therelations between the inner leads and the semiconductor chip shown inFIG. 1;

[0141]FIG. 8 is a section showing the schematic structure of the resinmolding according to another embodiment of the insulator shown in FIG.1;

[0142]FIG. 9 is a section taken along line II-II of FIG. 8;

[0143]FIG. 10 is a section showing the adhered portions of the resinmolding and the semiconductor chip of FIG. 8;

[0144]FIG. 11 is an exploded assembly view showing the relations amongthe semiconductor chip, the insulator and the lead frame shown in FIG.1;

[0145]FIGS. 12, 13 and 14 are diagrams for explaining thecharacteristics of mold resin materials;

[0146] FIGS. 15 to 19 are diagrams for explaining a package optimizedfor injecting the mold resin of the resin-sealed semiconductor deviceshown in FIG. 1 into a mold;

[0147]FIGS. 20, 21A, 21B, 22A and 22B are diagrams for explaining theschematic structure of a resin-sealed semiconductor device according toEmbodiment II of the present invention and a process for fabricating thesame;

[0148] FIGS. 23 to 28 are diagrams for explaining the schematicstructure of a resin-sealed semiconductor device according to EmbodimentIII of the present invention and a process for fabricating the same;

[0149]FIG. 29 is a partially sectional perspective view showing theschematic structure of a resin-sealed type semiconductor deviceaccording to Embodiment IV of the present invention;

[0150]FIG. 30 is a section taken along V-V of FIG. 29 and showing thestate before the resin molding;

[0151]FIG. 31 is a section showing a resin-sealed type semiconductordevice according to another embodiment before the resin molding in casea flexible/fluid substance of FIG. 29 is used;

[0152]FIGS. 32 and 33 are sections showing a resin-sealed typesemiconductor device according to another embodiment before the resinmolding in case a flexible/fluid substance is used;

[0153]FIG. 34 is a section showing a resin-sealed type semiconductordevice according to another embodiment before the resin molding in casea flexible/fluid substance is used;

[0154]FIG. 35 is a section showing the schematic section of aresin-sealed type semiconductor device according to Embodiment V of thepresent invention;

[0155]FIGS. 36A, 37A, 38A, 39A, 40A and 41A are top plan views takenfrom the opposite side to the modified principal surface of thesemiconductor chip of FIG. 35;

[0156]FIGS. 36B, 37B, 38B, 39B, 40B and 41B are sections taken along thetransverse center lines of FIGS. 36A, 37A, 38A, 39A, 40A and 41A;

[0157]FIG. 42 is a section showing another embodiment relating to theEmbodiment V;

[0158]FIG. 43 is a partially sectional perspective view showing theschematic structure of a resin-sealed type semiconductor deviceaccording to Embodiment VI of the present invention;

[0159]FIG. 44 is a section taken along line VI-VI of FIG. 43;

[0160]FIG. 45 is a partially sectional perspective view showing theschematic structure of a resin-sealed type semiconductor device modifiedfrom the Embodiment VI of the present invention;

[0161]FIG. 46 is a section taken along line VII-VII of FIG. 45;

[0162]FIG. 47 is a partially sectional perspective view showing theschematic structure of a resin-sealed type semiconductor device modifiedfrom the Embodiment VI of the present invention;

[0163]FIG. 48 is a section taken along line VIII-VIII of FIG. 47;

[0164]FIG. 49 is a partially sectional perspective view showing theschematic structure of a resin-sealed type semiconductor deviceaccording to Embodiment VII of the present invention;

[0165]FIG. 50 is a section taken along lien IX-IX of FIG. 49;

[0166]FIG. 51 is a top plan view showing the layout of the element ofthe semiconductor chip of the Embodiment VII and the layout of thebonding pads BP;

[0167]FIG. 52 is an overall top plan views showing the lead frame of theEmbodiment VII;

[0168]FIG. 53 is a top plan view showing the schematic structure of thelead frame of a resin-sealed type semiconductor device according toEmbodiment VIII of the present invention;

[0169]FIGS. 54A, 54B and 54C are sections showing the semiconductor chipfixing portions of the resin-sealed type semiconductor device accordingto the Embodiment VIII of the present invention, respectively;

[0170]FIGS. 55, 56 and 57 are sections showing the modifications of theresin-sealed type semiconductor device according to the Embodiment VIIIof the present invention before the resin molding;

[0171]FIGS. 58 and 59 are layouts of the semiconductor chips of theresin-sealed type semiconductor device according to Embodiment IX of thepresent invention;

[0172]FIG. 60 is a section for explaining the package of theresin-sealed type semiconductor device according to the Embodiment IX ofthe present invention;

[0173]FIG. 61 is a perspective view showing the side opposed to thewiring substrate of a resin-sealed type semiconductor device accordingto Embodiment X;

[0174]FIG. 62 is a section taken along line XI-XI of FIG. 61;

[0175]FIG. 63 is a section showing a modification of the resin-sealedtype semiconductor device of the Embodiment X;

[0176]FIGS. 64, 65, 66 and 67 are sections showing other modificationsof the semiconductor device of the Embodiment X;

[0177]FIGS. 68 and 69 are sections showing the state in which theresin-sealed type semiconductor device of the Embodiment X is packed inthe wiring substrate;

[0178]FIG. 70 is an overall perspective view showing the schematicstructure of the resin-sealed type semiconductor device for sealing theDRAM according to Embodiment XI of the present invention;

[0179]FIG. 71 is a partially sectional perspective view of FIG. 70;

[0180]FIG. 72 is a section taken along line XII-XII FIG. 74 and showinga semiconductor device according to one embodiment of the presentinvention;

[0181]FIG. 73 is a partially broken section taken along line XIII-XIIIof FIG. 74;

[0182]FIG. 74 is a general top plan view showing the semiconductordevice;

[0183]FIG. 75 is a general top plan view of a semiconductor chip showingthe circuit block of the semiconductor device;

[0184]FIG. 76 is a section taken along line XIV-XIV FIG. 77 and showinga semiconductor device according to another embodiment of the presentinvention;

[0185]FIG. 77 is a general top plan view showing the semiconductordevice;

[0186]FIG. 78 is a general top plan view of a semiconductor chip showingthe circuit block of the semiconductor device; and

[0187]FIG. 79 is a partially broken section showing a semiconductordevice according to another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0188] The present invention will be specifically described in thefollowing in connection with the embodiments thereof with reference tothe accompanying drawings.

[0189] Throughout all the drawings for explaining the embodiments, theportions having identical functions are designated at identicalreference characters, and their repeated descriptions will be omitted.

[Embodiment I]

[0190] A resin-sealed type semiconductor device for sealing a DRAMaccording to the embodiment I of the present invention is shown in FIG.1 (in partially sectional perspective view), in FIG. 2 (in top planview) and in FIG. 3 (in section taken along line I-I of FIG. 2).

[0191] As shown in FIGS. 1, 2 and 3, a DRAM (i.e., a semiconductor chip)1 is sealed with an SOJ (Small Outline J-bend) type resin-sealed package2. The DRAM 1 is made to have a large capacity of 16 (Mbits)×1 (bit) anda rectangular area of 16.48 (mm)×8.54 (mm). This DRAM 1 is sealed withthe resin-sealed package 2 of 400 (mil).

[0192] The DRAM 1 has its principal surface arranged mainly with amemory cell array and a peripheral circuit. The memory cell array isarranged in a matrix form with a plurality of memory cells (or elements)for storing information of 1 (bit), as will be described in detailhereinafter. The peripheral circuit is comprised of a direct peripheralcircuit and an indirect peripheral circuit. The direct peripheralcircuit is one for directly controlling the information writing andreading operations of the memory cells. This direct peripheral circuitincludes a row-address decoder, a column address decoder and a senseamplifier. The indirect peripheral circuit is one for controlling theoperations of the direct peripheral circuit indirectly. This indirectperipheral circuit includes a clock signal generator and a buffer.

[0193] The principal surface of the DRAM 1, i.e., the surface arrangedwith the memory cell array and the peripheral circuit is arranged withinner leads 3A. Insulating films 4 are sandwiched between the DRAM 1 andthe inner leads 3A. The insulating films 4 are made of a resin film ofpolyimide or the like. The individual surfaces of the insulating films 4at the sides of the DRAM 1 and the inner leads 3A are formed withadhesive layers. These adhesive layers are made of a resin such as apolyether amide-imide resin or an epoxy resin. The resin-sealed package2 of this kind adopts the LOC (Lead On Chip) structure in which theinner leads 3A are arranged over the DRAM 1. The resin-sealed typepackage 2 adopting this LOC structure can handle the inner leads 3Afreely without being restricted by the shape of the DRAM 1 so that itcan seal up the DRAM 1 having a size enlarged according to the freehandling. In other words, the resin-sealed package 2 adopting the LOCstructure can suppress the sealing (or package) size, even if the DRAM 1has its size enlarged according to the large capacity, thereby toenhance the packing density.

[0194] The inner leads 3A have their one-side ends made integral withouter leads 3B. These outer leads 3B are specified with signals to beapplied thereto, on the basis of the standards and are numbered. In FIG.1, the lefthand foremost one is the 1st terminal, and the righthandforemost one is the 14the terminal. The righthand rear one (the terminalnumber of which is shown at the inner lead 3A) is the 15the terminal,and the lefthand rear one is the 28th terminal. In short, theresin-sealed type package 2 is comprised of totally 24 terminals, i.e.,the 1st to 6th terminals, the 9th to 14th terminals, 15th to 20thterminals and 23th to 28th terminals.

[0195] The 1st terminal is one for a power source voltage V_(CC). Thispower source voltage V_(CC) is at 5 (V) for operating the circuit, forexample. The 2nd terminal is a data input signal terminal (D); the 3rdterminal is an idle terminal; the 4th terminal is a write enable signalterminal ({overscore (W)}); the 5th terminal is a row address strobesignal terminal ({overscore (RE)}); and the 6th terminal is an addresssignal terminal (A₁₁).

[0196] The 9th terminal is an address signal terminal (A₁₀); the 10thterminal is an address signal terminal (A₀); the 11th terminal is anaddress signal terminal (A₁); the 12th terminal is an address signalterminal (A₂); and the 13th terminal is an address signal terminal (A₃).The 14th terminal is a power source voltage V_(CC) terminal.

[0197] The 15th terminal is a reference voltage V_(SS) terminal. Thisreference voltage V_(SS) is at the reference level of 0 (V) of thecircuit. The 16th terminal is an address signal terminal (A₄); the 17thterminal is an address signal terminal (A₅); the 18th terminal is anaddress signal terminal (A₆); the 19th terminal is an address signalterminal (A₇); and the 20th terminal is an address signal terminal (A₈).

[0198] The 23th terminal is an address signal terminal (A₉); the 24thterminal is an idle terminal; the 25th terminal is a column addressstrobe signal terminal ({overscore (CAS)}); the 26th terminal is an idleterminal; and the 27th terminal is a data output signal terminal. The28th terminal is a reference voltage V_(SS) terminal.

[0199] The other-side ends of the inner leads 3A are extended across thelonger sides of the rectangular DRAM 1 to the center of the DRAM 1. Theother ends of the inner leads 3A have their extensions connected withbonding pads (or external terminals) BP arrayed at the center of theDRAM 1 through bonding wires 5. These bonding wires 5 are made ofaluminum (Al) but may be exemplified by gold (Au) wires, copper (Cu)wires or coated wires which are prepared by coating metal wires with aninsulating resin. The bonding wires 5 are bonded by the method using thehot contact bonding together with the ultrasonic vibrations.

[0200] Of the inner leads 3A, the 1st and 14th (V_(CC)) terminals 3A aremade integral with each other, and their central portions of the DRAM 1are extended in parallel with their longer sides (namely, the innerleads (V_(CC)) 3A are called the “common inner leads” or “bus bar innerleads”). Likewise, the 15th and 28th inner lead terminals (V_(SS)) 3Aare made integral with each other, and their central portions of theDRAM 1 are extended in parallel with their longer sides (namely, theseinner leads (V_(SS)) 3A are called the “common inner leads” or “bus barinner leads”). The inner leads (V_(CC)) 3A and the inner leads (V_(SS))3A are extended in parallel in the regions which are defined by theother-side leading ends of the remaining inner leads 3A. These innerleads (V_(CC)) 3A and inner leads (V_(SS)) 3A are so constructed as cansupply the power source voltage V_(CC) and the reference voltage V_(SS)in any position of the principal surface of the DRAM 1. In short, thisresin-sealed type semiconductor device is constructed to absorb thepower source noises easily and to speed up the operations of the DRAM 1.

[0201] The shorter side of the rectangular DRAM 1 is equipped with achip supporting lead 3C.

[0202] The inner leads 3A, the outer leads 3B and the chip supportinglead 3C are cut from the lead frame and are molded. This lead frame ismade of a Fe—Ni alloy (containing 42 to 50 (%) of Ni) or Cu.

[0203] The DRAM 1, bonding wires 5, inner leads 3A and chip supportinglead 3C thus far described are sealed up with a mold resin 2A. In orderto drop the stress, this mold resin 2A is exemplified by an epoxy resinto which are added a phenol hardener, silicone rubber and a filler. Thesilicone rubber has an action to drop the modulus of elasticity of theepoxy resin as well as the thermal expansion coefficient. The filler ismade of balls of silicon oxide and has an action to drop the thermalexpansion coefficient. On the other hand, the package 2 is formed in itspredetermined position with an index ID (in the form of a notch locatedat the lefthand end of FIGS. 1 and 2).

[0204] Next, the structure of the DRAM 1 sealed up with the resin-sealedtype package 2 is schematically shown in FIG. 4 (in a chip layout).

[0205] As shown in FIG. 4, the DRAM 1 is arranged substantially all overits surface with a memory cell array (MA) 11. The DRAM 1 of the presentembodiment I has its memory cell array coarsely divided into four memorycell arrays 11A to 11D, although not limitative thereto. As shown inFIG. 4, the two memory cell arrays 11A and 11B are arranged at the upperside of the DRAM 1 whereas the two memory cell arrays 11C and 11D arearranged at the lower side. Each of these four memory cell arrays 11A to11D is finely divided into sixteen memory cell arrays (MA) 11. In short,the DRAM 1 is arranged with sixty four memory cell arrays 11. Each ofthese sixty four memory cell arrays 11 has a capacity of 256 (Kbits).

[0206] Between every two of the sixty four memory cell arrays 11 of theDRAM 1, there is arranged a sense amplifier (SA) 13. This senseamplifier 13 is constructed of a complementary MOSFET (i.e., CMOS). Ofthe four memory cell arrays of the DRAM 1, each of the memory cellarrays 11A and 11B is arranged at its lower end with a column addressdecoder (YDEC) 12. Likewise, each of the memory cell arrays 11C and 11Dis arranged at its upper end with a column address decoder (YDEC) 12.

[0207] Of the four memory cell arrays of the DRAM 1, each of the memorycell arrays 11A and 11C is arranged at its righthand end with a worddriver (WD) 14, a row address decoder (XDEC) 15 and a unit matcontroller 16, which are disposed sequentially from the left to theright. Likewise, each of the memory cell arrays 11A and 11C is arrangedat its lefthand end with a word driver (WD) 14, a row address decoder(XDEC) 15 and a unit mat controller 16, which are disposed sequentiallyfrom the right to the left.

[0208] Each of the sense amplifier 13, column address decoder 12, worddriver 14 and row address decoder 15 described above constitutes of thedirect one of the peripheral circuits of the DRAM 1. This directperipheral circuit is one for directly controlling the memory cellswhich are arranged in the finely-divided memory cell arrays 11.

[0209] Peripheral circuits 17 and external terminals BP are interposedbetween the memory cell arrays 11A and 11B and between the memory cellarrays 11C and 11D of the four memory cell arrays of the DRAM 1. Theperipheral circuits 17 are exemplified by a main amplifier 1701, anoutput buffer 1702, a substrate potential generator (i.e., V_(BB)generator) 1703 and a power source circuit 1704. Totally sixteen mainamplifiers 1701 are arranged four at a unit. Totally four output buffers1702 are arranged.

[0210] The external terminals BP are arranged at the center of the DRAM1 because the aforementioned resin-sealed type semiconductor device 2 isconstructed to have the LOC structure so that the inner leads 3A areextended to the center of the DRAM 1. The external terminals 1 arearranged from the upper to the lower sides of the DRAM 1 within theregions which are defined by the memory cell arrays 11A and 11C, and 11Band 11D. The signals to be fed to the bonding pads (or externalterminals) BP have been described before in connection with theresin-sealed type semiconductor device 2 shown in FIG. 4, and theirdescriptions will be omitted here. Since the inner leads 3A fed with thereference voltage (V_(SS)) and the power source voltage (V_(CC)) arebasically extended from the upper to the lower sides on the surface ofthe DRAM 1, the DRAM 1 is arranged the plural external terminals BP forthe reference voltage (V_(SS)) and the power source voltage (V_(CC)) inthe extending direction thereof. In short, the DRAM 1 is so constructedas can feed the reference voltage (V_(SS)) and the power source voltage(V_(CC)) sufficiently. The data input signals (D), the data outputsignals (Q), the address signals (A₀ to A₁₁), the clock signals and thecontrol signals are concentrated at the center of the DRAM 1.

[0211] Peripheral circuits 18 are interposed between the memory cellarrays 11A and 11C and the memory cell arrays 11B and 11D of the fourmemory cell arrays of the DRAM 1. These peripheral circuits 18 areexemplified at a lefthand side by a row address strobe (RE) circuit1801, a write enable (W) circuit 1802, a data input buffer 1803, a powersource voltage (V_(CC)) limitter 1804, an X-address driver (or logicalstage) 1805, an X-redundancy circuit 1806, and an X-address buffer 1807.The righthand side of the peripheral circuits are exemplified by acolumn address strobe (CE) circuit 1808, a test circuit 1809, a VDLlimitter 1801, a Y-address driver (or logical stage) 1811, aY-redundancy circuit 1812 and a Y-address buffer 1813. The center of theperipheral circuits 18 are exemplified by a Y-address driver (or drivestage) 1814, an X-address driver (or drive stage) 1815 and a matselection signal circuit (or drive stage) 1816.

[0212] The aforementioned peripheral circuits 17 and 18 (and 16) areused as the indirect peripheral circuits of the DRAM 1.

[0213] Next, the detail of the lead frame will be described in thefollowing.

[0214] The lead frame of the present embodiment I is equipped, as shownin FIG. 1 and FIG. 5 (i.e., in a top plan view of the whole lead frame),with twenty signal inner leads 3A₁ and two common inner leads 3A₂. Theinner leads 3A (i.e., the signal inner leads 3A₁ and the common innerleads 3A₂) are so stepped that the gap between the portions of the innerleads 3A to be adhered to the insulating films (or members) 4 and thesemiconductor chip 1 is larger than the gap between the portion to bebonded to the insulating films (or members) 4 and the semiconductor chip1. Thanks to the stepped structure of the inner leads 3A, the straycapacity between the semiconductor chip and the leads is smaller thanthat of the prior art. As a result, it is possible to improve the signaltransmission rate and to drop the electrical noises.

[0215] On the other hand, the adhesion between the principal surface ofthe semiconductor chip 1 and the insulating film 4 and the adhesionbetween the insulating film 4 and the inner leads 3A are effected bymeans of an adhesive 7, as shown in FIG. 6. Alternatively, this adhesive7 may be used not for adhering the principal surface of thesemiconductor chip 1 and the insulating film 4 but only for adhering theinsulating film 4 and the inner leads 3A, as shown in FIG. 7.

[0216] Incidentally, the inner leads 3A can attain the aforementionedeffects even if they are applied to a package having none of the commoninner leads 3A₂.

[0217] In the predetermined positions of the lead frame, as shown inFIGS. 1 and 5, there are disposed the chip supporting (or suspending)leads 3C which are not supplied with any electric power but for adheringand fixing the principal surface of the semiconductor chip 1.

[0218] Since the semiconductor chip 1 is firmly fixed by adhering andfixing the principal surface of the semiconductor chip 1 by means of thesuspending leads 3C of no power supply, it is possible to improve thereliability and the moisture resistance of the semiconductor device.

[0219] Next, the detail of the insulating films 4 will be described inthe following.

[0220] The area of the principal surface of the semiconductor chip 1occupied by the insulating films 4 is at most one half of the area ofthe semiconductor chip 1. Since the area of the insulating films 4 isthus made at most one half of the area of the semiconductor chip 1, themoisture absorption by the insulating films 4 can be reduced to preventthe influences of both the heat during the reflow and the steam which isgenerated by the heat of the temperature cycle. In other words, thepackage can be prevented from being cracked to improve the reliabilityof the semiconductor device.

[0221] Since, moreover, the stray capacity between the semiconductorchip 1 and the leads is smaller than that of the prior art, it ispossible to improve the signal transmission rate and to drop theelectrical noises.

[0222] Still moreover, the aforementioned effects can be made moreprominent by practically minimizing the area of bonding the insulatingfilms 4 and the principal surface of the semiconductor chip 1. On theother hand, the leakage between the leads can be reduced because onlythe portions of the inner leads to be adhered to the semiconductor chipare covered with the insulating films.

[0223] On the other hand, the insulating films 4 over the principalsurface of the semiconductor chip 1 may be modified, as shown in FIG. 8,such that a resin molding 6 containing portions of the aforementionedinner leads 3A is used to sufficiently enlarge the gap between thesemiconductor chip 1 and the inner leads 3A thereby to reduce the straycapacity between the semiconductor chip 1 and the inner leads 3A.

[0224] Thus, the resin molding 6 and the mold resin 2A can be made ofthe material of good affinity so that the leads can be less peeled attheir interfaces.

[0225] The adhesion between the resin molding 6 and the semiconductorchip 1 may be effected by means of the adhesive 7, as shown in FIG. 10.

[0226] The base material of the insulating films 4 and the resin molding6 are molded of: one or more major components, which are selected froman epoxy resin, a BT (Bismaleimide Triazine) resin, a phenol resin(i.e., resol) and a polyimide resin (e.g., aromatic polyimide orcycloaliphatic polyimide containing ether and carbonyl bonds; and aninorganic filler, a fibrous hardener or various additives, if necessary.

[0227] Other examples of the base material of the insulating films 4 andthe resin molding 6 are molded of: a major component of a thermoplasticresin such as cycloaliphatic polyimide, polyester, polysulfone, aromaticpolyether amide, aromatic polyester imide, polyphenylene sulfide,polyamide-imide or its modified, polyether etherketone, polyethersulfone or polyether amide-imide; and an inorganic filler, fibers and anadditive, if necessary.

[0228] On the other hand, the adhesive for bonding the insulating films4 or the resin molding 6 to the inner leads 3A and the semiconductorchip 1 can be selected from one of: an epoxy resin, a BT resin, a phenolresin (or resol), a polyimide resin, an isomelanic resin and a siliconresin; a thermoset resin modified from the above-specified resins; and athermoplastic resin such as aromatic polyether amide,polyether-ether-ketone, polysulfone, aromatic polyester imide, polyesteror cycloaliphatic polyimide.

[0229] In the face mounting package type integrated circuit such as SOJ,the vapor-phase reflow solder method or the infrared reflow soldermethod is used in the case of solder packaging on a printed circuitboard (PCB). In this case, however, the moisture in the package may begasified and expanded by the reflow temperature (at 215 to 260° C.) topeel the adhesion at the chip interface until the the internal pressurein the peeled faces is raised to crack the sealing resin.

[0230] Since the LOC structure is made by bonding the inner leads 3A andthe semiconductor chip 1 with the insulating films 4 and the resinmolding 6, the aforementioned phenomena are accelerated by the moistureabsorption of the insulaitng films 4 or the resin molding 6. Foravoiding the phenomena, therefore, it is effective to reduce the volumeof the insulating films 4 thereby to decrease the moisture absorption.

[0231] The lower limit of the bonded area is that which can stand theexternal force to be borne at the wire bonding step and the resinmolding step.

[0232] Here will be examined the physical properties of the insulator ofthe aforementioned insulating films 4 or the resin molding 6.

[0233] The bonding insulating material to be used between the innerleads 3A and the semiconductor chip 1 of the semiconductor device havingthe LOC structure or the COL (Chip On Lead) structure has to satisfy atleast two of the following seven conditions:

[0234] (1) The saturated moisture absorption is equal to lower than thatof the sealing resin;

[0235] This condition is effective for preventing the resin crackingwhen in the vapor-phase solder (VPS).

[0236] (2) The dielectric constant is 4.0 or less (at 10³ Hz at the roomtemperature to 200° C.);

[0237] This condition reduces the stray capacity between the inner leadsand the semiconductor chip.

[0238] (3) The Barcol hardness at 200° C. is 20 or more;

[0239] This condition improves the wire bonding properties.

[0240] (4) The contents of U and Th are 1 ppb or less, and the amount ofan soluble halogen extracted at 120° C. for 100 hours is 10 ppm or less;

[0241] This condition is effective for preventing the soft error andimproving the moisture resistance.

[0242] (5) The contactness of the semiconductor chip and the inner leadsis excellent;

[0243] This condition can retain the wire bonding property, improve themoisture resistance and prevent the current leakage between the innerleads.

[0244] (6) The linear thermal expansion coefficient is 20×10⁻⁶/° C. orless; and

[0245] This condition reduces the warpage, in case an insulatingmaterial is bonded to the inner leads 3A, to improve the bondability tothe semiconductor chip at a subsequent step.

[0246] (7) The glass transition temperature Tg is 220° C. or higher inthe case of the thermoplastic resin.

[0247] This condition is effective for preventing the material having aglass transition temperature Tg of 220° C. or lower from being thermallydeformed at a high temperature (e g., 215° C.) in the reflow solder tocause a package cracking.

[0248] Examples of the material satisfying at least two of theabove-specified conditions will be described in the following.

[0249] For example, the film prepared by the following process was thematerial satisfying the above conditions except the item (1): Theprocess includes: the step of roughing the two sides of the Kapton 500 H(i.e., the polyimide film produced by Du Pont or Upilex S (i.e., thepolyimide film produced by Ube Kosan K.K.); and the step of coating thetwo sides with 25 microns of polyether amide having a glass transitiontemperature Tg of 220 or more.

[0250] The conditions (1) to (6) were satisfied by the film which wasprepared by applying and drying an adhesive of 10 to 25 microns, whichwas selected from an epoxy resin, a resol resin, an isomelamine resin, aphenol-modified epoxy resin and an epoxy-modified polyimide resin, tothe two sides of a bismaleimide, epoxy or epoxy-modified polyimide filmof 125 microns reinforced by highly pure quartz fibers or aramid fibers.

[0251] On the other hand, the following film satisfied all theconditions and was featured in its low moisture is absorptibity andsmall dielectric constant. The film was prepared: by improving theadhesiveness of the two sides of the film of Teflon PFA (i.e., acopolymer of tetraethylenefluoride-perfluoroalkoxy, Teflon EFP (i.e., acopolymer of tetraethylenefluoride-perhexapropylenefluoride) or KaptonF-type (i.e., the product of Toray and Du Pont, the Kapton film havingits two sides thinly coated with the Teflon FEP); and by coating the twosides of the film with an adhesive selected from an epoxy resin, a resolresin, an aromatic polyetheramide resin and a polyimide precursor.

[0252] Here will be described the method of adhering and fixing thesemiconductor chip to the lead frame 2 through the insulating films 4 bymeans of an adhesive.

[0253] As shown in FIG. 11 (in a development presenting the relationsamong the lead frame 3, the insulating films 4 and the semiconductorchip 1), the insulating films 4 are divided and adhered to thoseportions of the principal surface of the semiconductor chip 1, whichface the signal inner leads 3A, the common inner leads 3A₂ and thesuspending leads 3C, by means of the adhesive 7 (shown in FIGS. 1 and6). Next, as shown in FIG. 6, the signal inner leads 3A₁, the commoninner leads 3A₂ and the suspending leads 3C of the lead frame 3 arefixedly adhered by the adhesive 7.

[0254] The examples of the mold resin material (or resin) will bedescribed in the following:

[0255] (1) The resin composite to be used is exemplified by a thermosetresin which is blended with 70 wt. % of a substantially sphericalinorganic filler having a particle size distribution of 0.1 to 100microns, an average particle diameter of 5 to 20 microns and the maximumpacking density of 0.8 or more.

[0256] The resin component in this case may be any of epoxy, resol orpolyimide.

[0257] Thus, the mold resin material using the above-specified sphericalinorganic filler (e.g., molten silica) can be more blended to reduce thethermal expansion of the material, because its material exerts littleinfluence upon the molten viscosity and fluidicity, as shown in FIG. 12(plotting the relation between the packing density of the filter and thefluidicity). By increasing the loading of the filler, moreover, thethermal stress or the moldings can be dropped, as shown in FIG. 13(plotting the relations between the amount of synthesis of the fillerand the physical properties of the moldings) and FIG. 14 (plotting therelations between the amount of synthesis of the filler and the thermalstress). This improves the cracking resistance to a satisfactory extent.

[0258] Thus, it is possible to prevent a semiconductor device, which hasan especially the structure such as the LOC structure, from beingdeformed or damaged when it is to be molded.

[0259] (2) The resin compound to be used is comprised mainly of at leastone kind of a highly pure phenol-set type epoxy resin, resol type phenolresin and bismaleimide resin.

[0260] The properties of the set device in case the an unpurified resolresin is used are highly different from those of the purified devicesuch that the bulk resistance is different by three figures or more at140° C., as tabulated in Table 1 (as located at the tailing page).Because of much ionic impurity, moreover, there is also found a largedifference in the electric conductivity of an extracted liquid.

[0261] The purified resol resin was produced, for example, by pouring500 g of phenol, 550 g of formalin of 30% and 5 g of zinc acetate as ahardener into a flask, by gradually agitating and heating them, and bycirculating and heating them at 90° C. for 60 minutes. After this, theinside of the flask was evacuated to 20 mmHg, and the condensate and theunreacted components were removed. Next, 300 g of acetone was added todissolve the reaction products, and pure water was added to agitate themviolently at 50° C. for 30 minutes. After the cooling, the upper waterlayer was removed, and the reaction products were dissolved again into300 g of acetone. Pure water was then added to agitate them violently at50° C. for 30 minutes. After the cooling, the upper water layer wasremoved. These cleaning operations were repeated five times. After eachof these cleaning operations, the reaction products were partially takenout and dried at 40° C. for 48 hours under an evacuated condition, toproduce six kinds of resol type phenol resins of different degrees ofrefinement.

[0262] The number of purifications, the melting point and the settingcharacteristics of the resol type phenol resins thus obtained; theanalytical results of the hydrogen ion density (pH) and the electricconductivity of the extracted water, which was prepared by adding 50 gof pure water to 50 g of resol type phenol resins and by heating them at120° C. for 120 hours; and the analytical result of the concentration ofthe ionic impurities extracted are tabulated in Table 2 (as located atthe trailing page).

[0263] As is apparent from Table 2, the resol type phenol resins havingbeen subjected to the aforementioned cleaning operations by five timescontain remarkably small amounts of ion impurities.

[0264] Thus, the purifications can improve the reliabilities in themoisture resistance of the moldings, the hot lifetime of the Au/Albonded portions, and the characteristics of the element due to thedifferences in the aforementioned characteristics.

[0265] (3) The molding resin materials to be used are exemplified by theexamples 2 and 3 of Table 1, which are comprised mainly of resol typephenol resins or bismaleimide resins of high purity and whose moldingshave a bending strength of 3 kgf/mm² or more at 215° C.

[0266] Since the sealing materials using the resol type phenol resins orpolyimide resins of high purity have a high heat resistance for theirmoldings and a pending strength of 3 kgf/mm² or more at 215° C., thereflow resistance (to package cracking) in the case of the packageshaving absorbed the moisture and the reliabilites in the moistureresistance and the resistance to the thermal shocks are improved to aremarkably statisfactory extent.

[0267] (4) The inorganic filler to be blended into the base resin of theforegoing item (2) or (3) is exemplified by any of the Examples 1, 2 and3 of Table 1, i e., substantially spherical silica having a particlesize distribution of 0.1 to 100 microns, an average particle diameter of5 to 20 microns and the maximum packing density of 0.8 or more.

[0268] Thus, the sealing material using the above-specified sphericalmolten silica has its molten viscosity and fluidicity little influencedso that its thermal expansion can be drooped by increasing its loading.As a result, the package acquires an excellent cracking resistance inaddition to the effects of the foregoing item (2) and (3).

[0269] (5) The aforementioned resin sealing material is a composite, inwhich more than 67.5 vol. % of spherical molten silica having a particlesize distribution of 0.1 to 100 microns, an average particle diameter of5 to 20 microns and the maximum packing density of 0.8 or more isblended as the inorganic filler and whose molding has a linear expansioncoefficient of 1.4×10⁻⁵/° C. This resin sealing material is exemplifiedby any of the Examples 1, 2 and 3 of Table 1.

[0270] Thus, the aforementioned effects of the spherical molten silicacan be further improved.

[0271] (6) The aforementioned resin sealing material is exemplified byany of the Examples 1, 2 and 3 of Table 1, which is mixed with ionexchange water in an amount of ten times, and which has a pH of 3 to 7as an extracted liquid, in case it is extracted at 120° C. for 100hours, an electric conductivity of 200 μS/cm and an extraction of ionsof halogen, ammonia and metal of 10 ppm or less.

[0272] Next, one experiment of the Examples (1) to (6) of theabove-specified resin sealing materials will be described in thefollowing.

[0273] Three kinds of resin sealing materials were prepared, astabulated in Table 1: by using an epoxy resin, the resol type phenolresin (Example 1) and the bismaleimide resin (Example 2) as the basematerial of the thermoset resin; by adding to this base material bothspherical molten silica having a particle size distribution of 0.1 to100 microns, an average particle diameter of 5 to 20 microns and themaximum packing density of 0.90 as a filler and a variety of additives;by melting and heating the resultant mixture by a biaxial roll heated toabout 80° C.; and by pulverizing the heated mixture after a cooling.

[0274] Next, each of the resin sealing materials was used to mold asemiconductor device having the LOC structure shown in FIG. 1, i.e., the16M DRAM by a transfer molding machine. The molding process wasaccomplished at a mold temperature of 180° C., under a transfer pressureof 70 kgf/mm² and for a molding period of 90 secs.

[0275] According to the experiment, the following effects could beattained:

[0276] (1) The sealing material, which used as its filler thesubstantially spherical molten silica having the particle sizedistribution of 0.1 to 100 microns, the average particle diameter of 5to 20 microns and the maximum packing density of 0.8 or more, had alower molten viscosity and a better fluidicity than the sealing materialusing the generally existing square molten silica. During the moldingprocess, therefore, the bonding wires 5 of Au or the like and the leadframe 3 were neither deformed nor forced the semiconductor chip 1 toflow. In addition, the sealing material could fill up the narrow gap ofthe package excellently.

[0277] (2) The above-specified spherical molten silica exerted littleinfluence upon the molten viscosity and fluidicity of the material sothat the thermal expansion of the material could be dropped byincreasing the loading of the molten silica. As a result, the packagehad an excellent cracking resistance.

[0278] (3) In the semiconductor sealing material of the prior art, theepoxy resin was used, but the phenol resin or the polyimide resin werenot used, because the latter two resins contained many ionic impuritiesand were inferior in electric characteristics and the reliablities inthe moisture resistance so that they were not practical. If, however, ahighly pure resol type phenol resin or polyimide resin was used,satisfactory reliabilities could be attained.

[0279] (4) The sealing resin using the highly pure resol type phenolresin or polyimide resin had a high heat resistance in its molding formand was excellent especially in the mechanical strength at a hightemperature. As a result, the sealing resin was remarkably excellenteither in the reflow resistance (to package cracking) in case thepackage absorbed moisture or in the reliabilities in the moistureresistance and the resistance to the thermal shocks after the reflow.

[0280] Here will be described means for preventing formation of voidsand bending and charge shortage of the bonding wires when the resinsealing material is to be poured into a mold.

[0281] As shown in FIG. 1, the plural inner leads 3A are adhered to theprincipal surface of the semiconductor chip 1 through the insulatingfilms 4 for electrically insulating them from the semiconductor chip 1,by means of the adhesive 7. The inner leads 3A and the semiconductorchip 1 are electrically connected through the bonding wires 5 and aresealed up with the resin, thus producing the 16M DRAM. In this 16M DRAM,as shown in FIG. 15 (presenting the section of an essential portion ofFIG. 1), the package structure is made such that the distance H₁ betweenthe portion of the inner leads 3A adhered to the semiconductor chip 1and the outer wall of the package 2 is larger than the distance H₂between the side of the semiconductor chip opposite to thecircuit-formed side and the outer wall of the package.

[0282] Thanks to this package structure, as shown in FIG. 16 (presentingthe section of a model of FIG. 15), FIG. 17 (presenting the sectiontaken along line III-III of FIG. 16) and FIG. 18 (presenting the sectiontaken along line IV-IV of FIG. 16), the relations among the depths h₃₁and h₃₂ of flow paths of the upper portions of the inner leads 3A, thedepth h₂ of an intermediate portion between the inner leads 3A and thesemiconductor chip 1, and the depth h₁ of a flow path of the lowerportion of the semiconductor chip 1 are expressed by the followingEquations:

h ₁ =h ₂=(h _(c) −t _(c)−3W _(f) t _(f) /W _(c))/2(1−W/W _(c));

h ₃₁ =h _(c)−2h _(10r2) −t−t _(c);

[0283] and

h ₃₂ =h _(10r2) −t,

[0284] wherein:

[0285] h_(c): Cavity depth;

[0286] t_(c): Chip thickness;

[0287] t_(f): Lead frame thickness;

[0288] W_(c): Cavity width; and

[0289] W_(f): Length of the lead frame floating from the chip.

[0290] The above-specified Equations are graphically plotted in FIG. 19.

[0291] Thus, the resin flow passage or the package 2 is divided intothree: the upper flow path of the inner leads 3A; the intermediate flowpath between the inner leads 3A and the semiconductor chip 1; and thelower flow path of the semiconductor chip 1. The individual flow pathdepths and the resin flow path structures are so set as to equalize theaverage resin flow speeds in the individual flow paths. As a result, theaverage resin flow speeds in the flow paths, as indicated at circlednumerals 1, 2 and 3 in FIG. 17, can be equalized to prevent thegeneration of voids, the bending of the bonding wires (of Au) and thepacking shortage.

[0292] Since, moreover, the average flow speeds of the flow pathsdesignated at the circled numerals 1, 2 and 3 are equal, thesemiconductor chip 1 and the inner leads 3A can be prevented from beingdeformed so that a highly reliable package can be produced.

[Embodiment II]

[0293] In the semiconductor integrated circuit device according to theEmbodiment II of the present invention is constructed, as shown in FIG.20, FIGS. 21A and 21B and FIGS. 22A and 22B, the insulating films 4adhered to the principal surface of the semiconductor chip 1 of theforegoing Embodiment I are modified such that insulating films 4A arearranged all over or partially of those sides of the signal inner leads3A₁ and the common inner leads 3A₂, which are located in the closestposition to face the semiconductor chip 1.

[0294] More specifically, as shown in FIG. 20, the aforementionedinsulating films 4A are placed in advance all over the most closestsides of the signal inner leads 3A₁ and the common inner leads 3A₂facing the principal surface of the semiconductor chip 1 and are thenfixedly adhered to the semiconductor chip 1, when assembled.

[0295] The lead frame 3 thus carrying the insulating films 4A ismanufactured altogether with the signal inner leads 3A₁, the commoninner leads 3A₂ and the insulating films 4A by adhering the insulatingfilms 4 to that whole principal surface of the thin sheet for the innerleads, which is the closest to face the semiconductor chip 1, and byshaping and cutting the insulating films 4 by a press.

[0296] Thus, the area of the insulating films 4 can be reduced.Moreover, the signal inner leads 3A₁, the common inner leads 3A₂ and theinsulating films 4A can be held in predetermined positions. Furthermore,the signal inner leads 3A₁ and the common leads 3A₂ can be preventedfrom any leakage because no insulating film 4 is interposed inbetween.

[0297] Here, these insulating films 4 can be less influenced by thethermal stress, if divided into a plurality or four sheets, than theyare adhered in a single sheet.

[0298] As shown in FIG. 21A, moreover, of the whole (back) side facingand closest to the principal surface of the semiconductor chip 1, onlythe side portions corresponding to the signal inner leads 3A₁ and thecommon leads 3A₂ are arranged with the insulating films 4B. Then, thearea of the semiconductor chip 1 to be occupied by the insulating films4 can be minimized.

[0299] The lead frame 3 with the insulating films 4B occupying theminimum area of the semiconductor chip 1 is prepared, as shown in FIG.21B, by adhering four sheets of insulating films 4 having holes a inpredetermined positions, to the whole sides of the signal inner leads3A₁ and the common leads 3A₂ facing and closest to the principal surfaceof the semiconductor chip 1, and by shaping and cutting them by a pressto adhere the insulating films 4B to only the positions corresponding tothe bonding portions of the signal inner leads 3A₁ and the common leads3A₂.

[0300] As compared with the Embodiment shown in FIG. 20, the amount ofthe insulating films can be made smaller to reduce the moistureabsorption. Moreover, the semiconductor chip 1 can be fixed more easilywith the suspending leads.

[0301] In the embodiment shown in FIG. 21A, the insulating films 4A arearranged only in the portions corresponding to the bonding portions butmay be arranged partially in other portions, if necessary.

[0302] As shown in FIG. 22A, on the other hand, the insulating films 4Ashown in FIG. 20 are also arranged with insulating films 4C to extendand intersect the common inner leads 3A₂ and the signal inner leads 3A₁.

[0303] The inner leads 3A with the insulating films 4C are prepared, asshown in FIG. 22B, by forming one sheet of insulating film 4 havingholes b leaving only the portions corresponding to the signal innerleads 3A₁, and by cutting the insulating film 4 along the longitudinalcenter line into two halves. These two insulating film halves 4C areadhered to the common inner leads 3A₂ and the signal inner leads 3A₁.

[0304] Thus, it is sufficient to cut the insulating film 4 in advance inthe predetermined pattern to form the insulating films 4C and to adherethe insulating films 4C to the common inner leads 3A₂ and the signalinner leads 3A₁. As a result, the method of preparing the insulatingfilms 4C can be facilitated. Since, moreover, the insulating films 4Care adhered to the common inner leads 3A₂ and the signal inner leads3A₁, the leading ends of the signal inner leads 3A₁ can be flattened tofacilitate the subsequent working steps.

[0305] The adhesions between the insulating films 4C and the commoninner leads 3A₂ and the signal inner leads 3A₁ are effected by thecontact hot bonding in the case of a thermoplastic adhesive and areeffected by the and the principal surface of the semiconductor chip 1 isfurther formed with insulating films 4D on its portions to which atleast the signal inner leads 3A₁ and the common inner leads 3A₂ are tobe adhered.

[0306] The alpha ray shielding polyimide film 8 has a thickness of 2.0to 10.0 microns.

[0307] The insulating films 4D have a thickness of 75 microns or more.The resin suited for the insulating films 4D is exemplified by athremoset resin containing a printable inorganic filler.

[0308] The area occupied by the insulating films 4D is at most one halfof that of the semiconductor chip 1.

[0309] The semiconductor chip 1 is further formed with a polyimide film9 on the side opposed to its principal surface.

[0310] With reference to FIGS. 23 and 24A (presenting the flow chart offabrication and the sections of the individual steps), there will bedescribed one embodiment of the method of coating the whole region ofthe principal surface of the semiconductor chip 1 except the bondingpads BP of the principal surface of the semiconductor chip 1 with thealpha ray shielding polyimide film 8 and forming the insulating films 4Don the principal surface of the semicodnuctor chip 1 on its portions towhich at least the signal inner leads 3A₁ and the common inner leads 3A₂are to be adhered.

[0311] First of all, the alpha ray shielding polyimide film 8 is appliedto the whole region of a silicon wafer 10, as shown in FIG. 25(presenting the top plan view of the principal surface of the siliconwafer). After partially set, the polyimide film 8 is photo-etched toexpose the bonding pads (or external terminals) BP to the outside (asindicated at Step 101 in FIG. 24A).

[0312] Next, a solvent-peeling type dry film A is adhered (at Step 102).This solvent-peeling type dry film A is exposed (at Step 103) to apredetermined pattern and then developed (at Step 104) to form a hole B.

[0313] Next, a pasty insulating material (or printing paste) C isapplied, buried with (printing) squeeze and cured (at Steps 105, 106 and107). Then, the solvent-peeling type dry film A is peeled to form theinsulating films 4D. After this, a dicing is accomplished along thesolid lines over the silicon wafer 10 shown in FIG. 25, thus completingthe semiconductor chip with the insulating films 4D.

[0314] Another embodiment of the method of forming the aforementionedalpha ray shielding polyimide film 8 and the insulating films 4D isshown in FIG. 24B (presenting the fabrication flow chart and thesections of the chip at the individual steps). As shown, the alpha rayshielding polyimide film 8 is applied to the whole region of the siliconwafer 10 and is photo-etched to expose the bonding pads (or externalterminals) BP (at Step 201 in FIG. 24B).

[0315] Next, a dry film D for solder resists is adhered (at Step 202).This solder resist dry film D is exposed (at Step 203) to apredetermined pattern and is developed (at Step 204) to form theinsulating films 4D. After this, a dicing is accomplished along thesolid lines of the silicon wafer 10 shown in FIG. 25 to complete thesemiconductor chip with the insulating films 4D.

[0316] Incidentally, the silicon wafer 10 is not warped even if theinsulating films 4D having the aforementioned thickness are prepared bythe silicon wafer process, because the films 4D are formed onlypartially.

[0317] On the other hand, FIGS. 26 to 28 present various patterns of theinsulating films 4D to be formed in the portions of the principalsurface of the semiconductor chip 1, to which at least the leading endsof the signal inner leads 3A₁ and the common inner leads 3A₂, and thesuspending leads are to be adhered.

[0318] As is now apparent from the foregoing description, according tothe present Embodiment III, the whole region of the principal surface ofthe semiconductor chip 1 except the bonding pads (or external terminals)BP is coated with the alpha ray shielding polyimide film 8, and theprincipal surface of the semiconductor chip 1 is formed with theinsulating films 4D at the portions to which at least the leading endsof the signal inner leads 3A₁ and the common inner leads 3A₂ are to beadhered. As a result, the whole region of the circuit can be shieldedfrom the alpha ray shielding polyimide film 8, and the semiconductorchip 1 can be fixedly adhered by the insulating films 4D.

[0319] Since, moreover, the insulating films 4D are formed at theportions on the principal surface of the semiconductor chip 1, to whichat least the leading ends of the inner leads 3A and the suspending leads3C are adhered, it is possible to reduce the stray capacity between thesemiconductor chip 1 and the inner leads 3A.

[0320] Since, furthermore, the insulating films 4D are made of thethermoset resin containing the printable inorganic filler, they can beformed highly accurately during the wafer process.

[0321] Since, furthermore, the semiconductor chip 1 and the resin areexcellently adhered by forming the polyimide film 9 on the side of thesemiconductor chip 1 opposite to the principal surface, it is possibleto prevent the package cracking.

[0322] Furthermore, the insulating films 4D are formed highly accuratelyby the batch wafer process including the steps of: adhering thesolvent-peeling type dry film A to the silicon wafer 10; applying thepasty insulator (or printing paste) after the ordinary exposing anddeveloping steps; burying it with the squeeze; heating and curing it;and peeling the solvent-peeling type dry film. Thus, it is possible toimprove the productivity.

[0323] Since, furthermore, the insulating films 4D are formed only byexposing and developing the solder resist dry film D, the productivitycan be further improved.

[Embodiment IV]

[0324] The resin-sealed type semiconductor device according to theEmbodiment IV of the present invention is constructed, as shown in FIG.29 (presenting a perspective view in partial section): such that thesignal inner leads 3A₁ and the common inner leads 3A₂ are adhered to theprincipal surface of the semiconductor chip 1 of the foregoingEmbodiment I through the insulating films 4 for insulating themelectrically from the semiconductor chip 1; and such that the signalinner leads 3A₁, the common inner leads 3A₂ and the semiconductor chip 1are electrically connected through the bonding wires 5 and sealed with amold resin 2A. The semiconductor device is further constructed, as shownin FIG. 30 (presenting a section taken along lone V-V of FIG. 29 andshowing the state before molded with a resin), such that the principalsurface of the semiconductor chip 1 is so partially covered with asubstance 20, which is more flexible or fluid than the mold resin, as toshield all over the bonding wires 5, and such that the substance 20 issealed up at its outer side with the resin 2A.

[0325] More specifically, there is provided a dam 21 for covering allover the bonding wires 5 extending across the common inner leads 3A₂with the flexible/fluid substance 20. This substance 20 may be made offluid silicone gel, for example, and is dropped and set on the bondingwires 5 until it is sealed with the resin by the transfer mold.

[0326] The dam 21 is made of silicone rubber containing a highly viscoussilica filler.

[0327] On the other hand, the aforementioned flexible/fluid substance 20need not always be the above-specified gel but may be exemplified byvarious materials such as silicone grease or rubber if it has such aflexibility or fluidicity as to deform the bonding wires 5 therein.Thus, the bonding wires 5 can freely follow the deformations, even ifthe principal surface of the semiconductor chip 1 is peeled to expandthe steam when the package having absorbed moisture is to be subjectedto the reflow soldering treatment, so that they can be prevented frombeing broken.

[0328] Moreover, the bonding wires 5 are suppressed from being deformedduring the transfer molding of the mold resin 2A. Even if the wires 5are extended to run across the common inner leads 3A₂, the bonding wires5 can be prevented from being deformed during the molding, from beingshorted to each other or from contacting with the common inner leads3A₂.

[0329] On the other hand, the substance covering the bonding wires 5need not be the flexible/fluid substance if it is used with a view topreventing the deformations of the bonding wires 5. The substance may beexemplified by an epoxy resin having a modulus of elasticity as high asthat of the outer resin 2A transfer-molded, if it can pot the bondingwires 5 over the principal surface of the semiconductor chip 1.

[0330] In case the flexible/fluid substance 20 has a fluidicity, itsviscosity has to be higher than the molten viscosity of the resin 2A inthe transfer mold.

[0331] Since, moreover, the resin 2A is kept away from direct contactwith the bonding wires 5 by the flexible/fluid substance 20, the bondingwires 5 are prevented from being repeatedly deformed in the temperaturecycle by the relative thermal deformations between the semiconductorchip 1 and the mold resin 2A so that they are not broken by the fatigue.

[0332] In case the flexible/fluid substance 20 is used, the bonding padsBP are presented from having their surfaces gapped by the thermal stressso that their aluiminum can be prevented from being corroded by themoisture.

[0333]FIG. 31 is a section showing the state before the resin moldshowing the resin-sealed type semiconductor device according to anotherembodiment in case the flexible/fluid substance 20 is used.

[0334] Since the interfaces between the signal inner leads 3A₁ and theresin 2A are more reluctant to be gapped than the principal surface ofthe semiconductor chip 1, as shown in FIG. 31, the bonding portions ofthe bonding wires 5 at the side of the signal inner leads 3A₁ are lessbroken. According to this embodiment, therefore, only the (first)bonding portions liable to be broken at the semiconductor chip 1 areformed with the flexible/fluid substance 20. As a result, a breakpreventing effect can be attained to some extent if the bonding wires 5can be freely deformed.

[0335] Moreover, this embodiment makes use of the common inner leads 3A₂in place of the foregoing dam 21 of FIG. 30.

[0336] Since, in the case of this embodiment, all the bonding wires 5are not covered with the flexible/fluid substance 20, they are subjectedto repeated deformations by the relative thermal deformations betweenthe semiconductor chip 1 and the mold resin 2A, in case the package isheld in the temperature cycle, so that they are more liable to be brokendue to fatigue than those of the embodiment of FIG. 30.

[0337] Since, moreover, the flexible/fluid substance 20 can be made lessand lower, it is possible not only to prevent the disconnections duringthe reflow soldering operations and the wire deformations during thetransfer mold but also to thin the package as a whole thereby to improvethe packing density. FIG. 32 is a section showing the state before theresin mold of the resin-sealed type semiconductor device according toanother embodiment of the present invention in case the flexible/fluidsubstance 20 is used.

[0338] According to this embodiment, as shown in FIG. 32, all thebonding wires 5 are covered to shield all over the principal surface ofthe semiconductor chip 1 with the flexible/fluid substance 20.

[0339] Effects similar to those of the foregoing embodiment of FIG. 30can be attained, and the whole region of the principal surface of thesemiconductor chip 1 is covered with the flexible/fluid substance 20 sothat the moisture resistance can be better improved.

[0340] Since, however, the flexible/fluid substance 20 has a largesurface area, the interfaces with the mold resin 2A are gapped duringthe reflow soldering operation so that the upper mold resin 2A is liableto be cracked when it is exposed to a vapor pressure.

[0341]FIG. 33 is a section showing the state before the resin mold ofthe resin-sealed type semiconductor device of another embodiment in casethe flexible/fluid substance 20 is used.

[0342] According to this embodiment, as shown in FIG. 33, all thebonding wires 5 mounted over the principal surface of the semiconductorchip 1 are covered with the substance 20 which is more flexible or fluidthan the mold resin 2A.

[0343] The flexible/fluid substance 20 covering the bonding wires 5 neednot be shaped to rise on the principal surface of the semiconductor chip1 but may be applied to only the surfaces of the bonding wires 5.

[0344] In order to effect such coverage, the flexible/fluid substance 20is first diluted to a low viscosity with a solvent and is then droppedto the semiconductor chip 1 to cover the bonding wires 5. After this,the solvent is evaporated to make the coverage.

[0345] In this case, the thicker layer of the flexible/fluid substanceover the surfaces of the bonding wires 5 has the better effects forpreventing the disconnections and the deformations of the bonding wires5.

[0346] Thanks to this structure, the amount of the flexible/fluidsubstance 20 for attaining the effects similar to those of the foregoingembodiment shown in FIG. 30 can be reduced to prevent the package crackwhich might otherwise be caused by the vapor pressure between theflexible/fluid substance 20 and the mold resin 2A.

[0347]FIG. 34 is a section before the resin mold of the resin-sealedtype semiconductor device according to another embodiment in case theflexible/fluid substance 20 is used.

[0348] According to this embodiment, as shown in FIG. 34, the bondingwires 5 are covered with the flexible/fluid substance 20, and the moldresin 2A at the side opposite to the principal surface of thesemiconductor chip 1 is bored with a hole 22 to expose a portion of thesemiconductor chip 1 substantially to the outside.

[0349] Here, the word “substantially” imagines the inevitable existenceof either a thin cover film of the mold resin 2A at the side opposite tothe principal surface of the semiconductor chip or such a thin resinlayer as will be easily broken in case the steam pressure is establishedin the package 2.

[0350] Since the moisture resistance of the bonding pads BP can beretained by the flexible/fluid substance 20 without breaking the bondingwires 5 in the temperature cycle when in the reflow solderingoperations, it is not degraded even if the hole 22 is formed in theportion of the mold resin 2A.

[0351] Since, moreover, the steam generated in the package during thereflow soldering operation is released through the hole 22 to theoutside, the pressure is not built up to prevent the resin cracking.

[0352] Furthermore, the side of the hole opposite to the principalsurface of the semiconductor chip 1 need not be completely exposed butmay be clogged with the mold resin 2A if this resin 2A can be easilycleared by the vapor pressure.

[0353] As is now apparent from the description thus far made, accordingto the embodiment IV, the bonding wires 5 can be prevented from beingbroken, even if the principal surface of the semiconductor chip 1 ispeeled to expand the steam during the reflow soldering operation.

[0354] It is also possible to prevent the bonding wires 5 from beingshorted during the transfer mold or from contacting with the commoninner leads 3A₂.

[0355] The resin cracking during the reflow soldering operation can beprevented without degrading the moisture resistance of the bonding padsBP and causing the disconnections of the bonding wires 5 in thetemperature cycle.

[Embodiment V]

[0356] The resin-sealed type semiconductor device according to theEmbodiment V of the present invention is modified from the resin-sealedtype semiconductor device of the foregoing Embodiment I such that theside of the semiconductor chip 1 opposite to the principal surface isrecessed or raised at 101, i.e., formed with a round recess, as shown inFIG. 35 (presenting a section).

[0357] The mold resin 2A is restrained on the semiconductor chip 1 bythat recess 101 so that the reflow cracking can be prevented by reducingthe stress which is to be established in the mold resin portions of thecorners of the side of the semiconductor chip 1 opposed to the principalsurface.

[0358] Here, the recess 101 may be formed by the etching or anothermethod.

[0359]FIG. 36A (presenting a top plan view taken from the side oppositeto the principal surface of FIG. 3) and FIG. 36B (presenting sectiontaken on the transverse center line of FIG. 26A) show a modification ofthe recess 101 which is formed in the side opposite to the principalsurface of the semiconductor chip 1. In this modification, an annularrecess 101 a is formed in the side opposite to the principal surface ofthe semiconductor chip 1.

[0360]FIG. 37A (presenting a top plan view) and FIG. 37B (presenting asection) show another modification of the recess 101 which is formed inthe side opposite to the principal surface of the semiconductor chip 1.In this modification, a square recess 101 b is formed in the sideopposite to the principal surface of the semiconductor chip 1.

[0361]FIG. 38A (presenting a top plan view) and FIG. 38B (presenting aside elevation) show another modification of the recess 101 which isformed in the side opposite to the principal surface of thesemiconductor chip 1. In this modification, a round rise 101 c is formedin the side opposite to the principal surface of the semiconductor chip1.

[0362]FIG. 39A (presenting a top plan view) and FIG. 39B (presenting aside elevation) show another modification of the recess 101 which isformed in the side opposite to the principal surface of thesemiconductor chip 1. In this modification, a square rise 101 d isformed in the side opposite to the principal surface of thesemiconductor chip 1.

[0363]FIG. 40A (presenting a top plan view) and FIG. 40B (presenting aside elevation) show another modification of the recess 101 which isformed in the side opposite to the principal surface of thesemiconductor chip 1. In this modification, an elliptical recess 101 eis formed in the side opposite to the principal surface of thesemiconductor chip 1.

[0364]FIG. 41A (presenting a top plan view) and FIG. 41B (presenting aside elevation) show another modification of the recess or rise 101which is formed in the side opposite to the principal surface of thesemiconductor chip 1. In this modification, recesses or rises 101 f areformed in the groove shape in the side opposite to the principal surfaceof the semiconductor chip 1. The grooves may take in the form of alattice.

[0365] Since one of the recesses or rises 101 a to 101 f is formed inthe side opposite to the principal surface of the semiconductor chip 1,as has been described above, the semiconductor chip 1 can be firmlyrestricted by the mold resin 2A.

[0366] It is also possible to reduce the stress which is generated inthe mold resin 2A by the corner portions at the side opposite to theprinciple surface of the semiconductor chip 1.

[0367]FIG. 42 shows another embodiment according to the presentinvention and belonging to the Embodiment V. The aforementioned recessor rise 101 is formed in the side opposite to the principal surface ofthe semiconductor chip 1 while leaving an silicon oxide film 102 on theside opposite to the principal surface of the semiconductor chip 1 ofthe Embodiment V.

[0368] Since the silicon oxide film 102 is thus left on the sideopposite to the principal surface of the semiconductor chip 1, theadhesion between the silicon oxide film 102 and the mold resin 2A is sostrong that the mold resin 2A can be prevented from being peeled offfrom the side opposite to the principal surface of the semiconductorchip 1.

[0369] Thanks to the recess or rise 101, moreover, the semiconductorchip 1 can be firmly restricted by the mold resin 2A.

[Embodiment VI]

[0370] The resin-sealed type semiconductor device according to theEmbodiment VI of the present invention is constructed, as shown in FIG.43 (presenting a perspective view in partial section) and FIG. 44(presenting a section taken along line VI-VI of FIG. 43): such that thesignal inner leads 3A₁ and the common inner leads 3A₂ are adhered to theprincipal surface of the semiconductor chip 1 of the foregoingEmbodiment I through the insulating films 4 for insulating themelectrically from the semiconductor chip 1; and such that the signalinner leads 3A₁, the common inner leads 3A₂ and the semiconductor chip 1are electrically connected through the bonding wires 5 and sealed with amold resin 2A. The semiconductor device is equipped at the longitudinalcenters of the sides of the package 2 with radiating leads 301 a whichare insulated from the semiconductor chip 1 and which have theirone-side ends extended to above the exothermic portions of the principalsurface of the semiconductor chip 1 and their other ends extended tobelow the outside of the side of the package 2 opposite to the principalsurface of the semiconductor chip 1.

[0371] Thus, the one-side ends of the radiating leads 301 a electricallyinsulated from the semiconductor chip 1 are extended at the longitudinalcenters of the sides of the package to above the exothermic portions ofthe principal surface of the semiconductor chip 1, and the other ends ofthe radiating leads 301 a are extended to below the outside of thepackage 2 opposite to the principal surface of the semiconductor chip 1,so that the radiation efficiency of the exothermic portions of thesemiconductor chip 1 can be improved.

[0372]FIG. 45 (presenting a perspective view in partial section) andFIG. 46 (presenting a section taken along line VII-VII of FIG. 45) showa modification of the radiating leads 301 a shown in FIG. 43. Themodified radiating leads 301 b have their one-side ends extended toabove the exothermic portions of the principal surface of thesemiconductor chip 1 and their other ends extended to above the outsideof the package 2 at the side of the principal surface of thesemiconductor chip 1.

[0373] The radiating leads 301 b have their extensions providing theradiating plates.

[0374] Thus, at the longitudinal centers of the sides of the package,the one-side ends of the radiating leads 301 b electrically insulatedsemiconductor chip 1 are extended to above the exothermic portions ofthe principal surface of the semiconductor chip1, and the other ends ofthe radiating leads 301 b are extended to above the outside of thepackage 2 at the side of the principal surface of the semiconductor chip1, so that the radiating efficiency of the exothermic portions of thesemiconductor chip 1 can be improved.

[0375] Here, the other ends of the radiating leads 301 b extended toabove the outside of the package 2 at the side of the principal surfaceof the semiconductor chip 1 may be folded to have their volumes reduced,as indicated by broken lines in FIG. 46.

[0376] On the other hand, the lead frames for the aforementionedradiating leads 301 a and 301 b are fabricated integrally with thesignal lead frame.

[0377]FIG. 47 (presenting a perspective view in partial section) andFIG. 48 (presenting a section taken along line VIII-VIII of FIG. 48)show a modification of the Embodiment VI shown in FIG. 39. In thismodification, radiating leads 301 c have their one-side ends extended tothe sides opposite to the exothermic portions of the principal surfaceof the semiconductor chip 1 and their other ends extended to below theoutside of the package 2 opposite to the principal surface of thesemiconductor chip 1.

[0378] Thus, at the longitudinal centers of the sides of the package,the one-side ends of the radiating leads 301 c electrically insulatedfrom the semiconductor chip 1 are extended to the sides opposite to theexothermic portions of the principal surface of the semiconductor chip1, and the other ends of the radiating leads 301 c are extended to belowthe outside of the package 2 opposite to the principal surface of thesemiconductor chip 1, so that the radiating efficiency of the exothermicportions of the semiconductor chip 1 can be improved.

[0379] The one-side ends of the radiating leads 301 c need not always beelectrically insulated from the semiconductor chip 1 by means of theinsulating film.

[0380] In this case, moreover, the lead frame of the radiating leads 301c is fabricated separately of the signal lead frame.

[Embodiment VII]

[0381] The resin-sealed type semiconductor device according to theEmbodiment VII of the present invention is constructed, as shown in FIG.49 (presenting a perspective view in partial section) and FIG. 50(presenting a section taken along line IX-IX of FIG. 49): such that thesignal inner leads 3A₁ and the common inner leads 3A₂ are adhered to theprincipal surface of the semiconductor chip 1 of the foregoingEmbodiment I shown in FIG. 1 through the insulating films 4 forinsulating them electrically from the semiconductor chip 1; and suchthat the signal inner leads 3A₁, the common inner leads 3A₂ and thesemiconductor chip 1 are electrically connected through the bondingwires 5 and sealed with a resin. In this semiconductor device, theprincipal surface of the semiconductor chip 1 is arranged with thebonding pads BP which do not intersect the bonding wires 5 and thecommon inner leads 3A₂ arranged on the principal surface.

[0382] The element layout and bonding pads BP of the semiconductor chip1 of the present Embodiment VII are shown in FIG. 51 (presenting alayout top plan view).

[0383] Specifically, the memory array (MA) is arranged substantially allover the area of the DRAM 1. In this DRAM 1 of the present embodimentVII, the memory cell array is coarsely divided into eight memory cellarrays 11A to 11H, although not limitative thereto. As shown in FIG. 51,the four memory cell arrays 11A, 11B, 11C and 11D are arranged at theupper side of the DRAM 1, and the four memory cell arrays 11E, 11F, 11Gand 11H are arranged at the lower side. Each of these eight memory cellarrays 11A to 11H is further finely divided into sixteen memory cellarrays (MA) 11. In short, the DRAM 1 is arranged with one hundred andtwenty eight memory cell arrays 11E. Each of the 128 memory cell arrays11 has a capacity of 128 [Kbits].

[0384] The sense amplifier (SA) 13 is interposed between the two of the128 memory cell arrays 11 of the DRAM 1. The sense amplifier 13 isconstructed of a complementary MOSFET (CMOS). The column address decoder(YDEC) 12 is arranged at one lower end of each of the four 11A, 11B, 11Cand 11D of the eight memory cell arrays of the DRAM 1. Likewise, thecolumn address decoder (YDEC) 12 is arranged at one upper end of each ofthe memory cell arrays 11E, 11F, 11G and 11H.

[0385] The peripheral circuit 17 and the external terminals BP areinterposed between the two 11A and 11B, the two 11C and 11D, the two 11Eand 11F, and the two 11G and 11H of the eight memory cell arrays of theDRAM 1. On the other hand, the peripheral circuits 17 and the peripheralcircuits 18 are disposed at the individual lower regions of the memorycell arrays 11A, 11B, 11C and 11D and at the individual upper regions ofthe memory cell arrays 11E, 11F, 11G and 11H. The peripheral circuits 17are exemplified by a main amplifier, an output buffer circuit, asubstrate potential generator (or V_(BB) generator) and a power sourcecircuit.

[0386] The peripheral circuit 18 is further exemplified by a row addressstrobe (RAS) circuit, a write enable (WE) circuit, a data input buffer,a V_(CC) limitter, an X-address driver (i.e., logical stage), anX-redundancy circuit, an X-address buffer, a column address strobe (CAS)circuit, a test circuit, a VDL limitter, a Y-address driver (i.e.,logical stage), a Y-redundancy circuit, a Y-address buffer, a Y-addressdriver (i.e., drive stage), an X-address driver (i.e., drive stage), anda mat selecting signal circuit (i.e., drive stage) (as should bereferred to FIG. 4 and its description).

[0387] Since the aforementioned resin-sealed type semiconductor device 2is constructed to have the LOC structure and since the inner leads 3Aare extended to the central portion of the DRAM 1, the externalterminals BP are arranged at the central portion of the DRAM 1 and onthe principal surface of the semiconductor chip 1 such that they arekept away from intersecting the bonding wires 5 and the common innerleads 3A₂ arranged on the principal surface of the semiconductor chip 1.

[0388] The external terminals BP are arranged within the regions definedby the memory cell arrays 11A, 11B, 11C, 11D, 11E, 11F, 11G and 11H fromthe upper to the lower ends of the DRAM 1. The signals to be applied tothe external terminals BP will not be described here because they havebeen described in connection with the resin-sealed type semiconductordevice 2 shown in FIG. 1.

[0389] Since the inner leads 3A supplied with the reference voltage(V_(SS), and the power source voltage (V_(CC)) are extended from theupper to the lower ends of the surface of the DRAM 1, the DRAM 1 isarranged with the plural external terminals BP for the reference voltage(V_(SS)) and the power source voltage (V_(CC)) in the extendingdirection. In short, the DRAM 1 is constructed to effect sufficientsupply of the reference voltage (V_(SS)) and the power source voltage(V_(CC)).

[0390] As has been described above, according to the present EmbodimentVII, the principal surface of the semiconductor chip 1 is arranged withthe bonding pads BP which do not intersect with the bonding wires 5 andthe common inner leads 3A₂ arranged on the same surface. Thus, it ispossible to prevent the shorting between the bonding wires 5 forconnecting the signal inner leads 3A₁ and the semiconductor chip 1 andthe common inner leads 3A₂.

[0391] Next, the lead frame will be described in detail in thefollowing.

[0392] As shown in FIG. 52 (presenting an overall top plan view of thelead frame), the lead frame 3 of the present Embodiment VII is equippedwith twenty signal inner leads 3A₁ and two common inner leads 3A₂. Theinner leads 3A₁ are stepped, as shown in FIG. 50 (presenting a section),such that the gap between their portions nearer the outer leads 3B thantheir portions contacting with the insulating films 4 and thesemiconductor chip is larger than the gap between their portionscontacting with the insulating films (or insulators) 4 and thesemiconductor chip 1. By thus adopting the stepped structure in thesemiconductor chip 1, the stray capacity between the semiconductor chip1 and the signal inner leads 3A₁ can be reduced to a lower level thanthat of the prior art to improve the signal transmission rate and todrop the electrical noises.

[0393] The present Embodiment VII is identical to the foregoingEmbodiment I except the arrangement of the bonding pads BP on theprincipal surface of the semiconductor chip 1 and the lead frame.

[0394] Incidentally, the techniques of the foregoing Embodiments II-VIcan naturally be applied to the present Embodiment VII.

[Embodiment VIII]

[0395] The resin-sealed type semiconductor device according to theEmbodiment VIII of the present invention is, as shown in FIG. 53 (planpresenting the schematic mechanism of the lead frame in Embodiment VIII)a modification of the lead frame of the foregoing Embodiment I, in whichinner leads 3C₁ (suspending leads) to be supplied with no power arefolded to fix the side of the semiconductor chip 1 opposite to theprincipal surface.

[0396] As shown in FIG. 54A (presenting a section showing thesemiconductor chip fixing portion) and FIG. 56 (presenting a sectionshowing the signal inner leads and the common inner leads before theresin molding), moreover, the semiconductor chip 1 is adhered and fixedwith the adhesive 7 by the suspending leads 3C₁ such that the signalinner leads 3A₁ and the common inner leads 3A₂ are arranged in floatingstates from the principal surface of the semiconductor chip 1.

[0397] The adhesive 7 may be any of the aforementioned adhesives such asepoxy resins or resol resins.

[0398] On the other hand, the adhesions may be effected through theinsulating films 4 between the suspending leads 3C₁ and thesemiconductor chip 1.

[0399] In this case, the connections of the signal inner leads 3A₁ andthe common inner leads 3A₂ and the bonding pads BP of the semiconductorchip 1 by means of the bonding wires 5 are accomplished by holding thesignal inner leads 3A₁ and the common inner leads 3A₂ on thesemiconductor chip 1 by means of a jig. If the holding jig is removedafter the wire bondings, the signal inner leads 3A₁ and the common innerleads 3A₂ are brought into the state shown in FIG. 56 by the spring-backeffect of the suspending leads 3C₁.

[0400] As shown in FIG. 54B, on the other hand, the signal inner leads3A₁ and the common inner leads 3A₂ may be arranged in a floating statefrom the principal surface of the semiconductor chip 1 (as shown in FIG.56) by sandwiching the insulating films 4 of a predetermined thicknessbetween the suspending leads 3C of the lead frame 3 applied to theforegoing Embodiment I and the principal surface of the semiconductorchip 1 and adhering them by means of the adhesive 7. In this case, theinsulating films 4 ordinarily have a thickness of 150 microns but canhave a larger thickness.

[0401] As shown in FIG. 55 (presenting a section showing the statebefore the resin molding), on the other hand, insulating plates 40 maybe sandwiched between the signal inner leads 3A₁ and the common innerleads 3A₂ and the principal surface of the semiconductor chip 1 toconnect the signal inner leads 3A₁, the common inner leads 3A₂ and thesemiconductor chip 1 electrically by the bonding wires 5 and to sealthem up with the mold resin.

[0402] As shown in FIG. 57 (presenting a section showing the statebefore the resin molding), moreover, the insulating plate 40 may besandwiched only between the one-side, e.g., lefthand signal inner lead3A₁ and common inner lead 3A₂ and the semiconductor chip 1, whereas therighthand signal inner lead 3A₁ and common inner lead 3A₂ and thesemiconductor chip 1 may be electrically connected through the bondingwires 5 and sealed with the mold resin such that the signal inner lead3A₁ and the common inner lead 3A₂ are floating from the principalsurface of the semiconductor chip 1.

[0403] In order that the signal inner leads 3A₁ and the common innerleads 3A₂ may be arranged an a floating state from the principal surfaceof the semiconductor chip 1 (as shown in FIG. 56), as shown in FIG. 54C,the suspending leads 3C₁ may be deeply folded to form suspending leads3C₂ for fixedly adhering the side of the semiconductor chip 1 oppositeto the principal surface. As a result, the side of the semiconductorchip 1 opposite to the principal surface is adhered and fixed by thesuspension leads 3C₂ so that the signal inner leads 3A₁ and the commoninner leads 3A₂ are floating from the principal surface of thesemiconductor chip 1, thus eliminating the step of adhering theinsulating films 4. Moreover, the semiconductor chip 1 is firmly fixed.Since no lead line is adhered to the memory cells, it is possible toreduce the breakage of the memory cells.

[0404] As has been described above, according to the present EmbodimentVIII, the moisture absorption can be reduced by eliminating orminimizing the use of the insulating films 4 to make the solder reflowresistance advantageous.

[0405] In the Embodiment VIII, it is preferable to apply the alpha rayshielding polyimide film to the whole region of the principal surface ofthe semiconductor chip 1 except the bonding pads.

[Embodiment IX]

[0406] In the resin-sealed type semiconductor device according to theEmbodiment IX of the present invention, as shown in FIGS. 58 and 59(presenting layouts of the semiconductor chip), there are provided twosemiconductor chips 1A and 1B which are formed in a mirror symmetry withthe bonding pads BP (or solder bumps) connected with the inner leads.

[0407] In FIG. 58, the CAS0 terminals (i.e., bonding pads BP) and theCAS1 terminals (i.e., bonding pads BP) are shared, and the otherterminals (i.e., bonding pads BP) are held in common. This layoutdoubles the capacity in the word direction.

[0408] In FIG. 59, the Do terminals and the Di terminals are shared,whereas the other terminals are held in common. This layout doubles thecapacity in the bit direction.

[0409] As shown in FIG. 60 (presenting a section for explaining thepackage), moreover, at the sides of the individual principal surfaces ofthe two semiconductor chips 1A and 1B and across the inner leads 3A,these inner leads 3A and the bonding pads BP of the semiconductor chip 1are electrically connected through the solder bumps 5C and sealed upwith the mold resin.

[0410] Thus, in the two semiconductor chips 1A and 1B formed in themirror symmetry with the inner leads 3A and the bonding pads BP, theinner leads 3A and the bonding pads BP of the semiconductor chip 1 areelectrically connected at the sides of the individual principal surfacesand across the inner leads 3A through the solder bumps 5C and sealed upwith the mold resin so that an element having a twice capacity can bepackaged without changing the contour of the package 2.

[Embodiment X]

[0411] In the resin-sealed type semiconductor device according to theEmbodiment X of the present invention, as shown in FIG. 61 (presenting aperspective view taken from the side opposed to the wiring substrate ofthe resin-sealed type semiconductor device of the Embodiment X) and FIG.62 (presenting a section taken along line XI-XI of FIG. 61), the package2 of the semiconductor device of the foregoing Embodiment I is formed,at its side facing the substrate, with a radiating groove 50 which isopened to the outside. In this case, the distance between the bottom 50Aof the radiating groove 50 and the semiconductor chip 1, i.e., thethickness of the mold resin 2A below the semiconductor chip 1 is set at0.3 mm or less.

[0412] By forming the radiating groove 50, as shown in FIGS. 68 and 69(presenting sections showing the state in which the resin-sealed typesemiconductor device of the Embodiment X is packed in the wiringsubstrate), the gap 51D between a substrate 51A or 51B and the bottom50A of the radiating groove 50 is so enlarged that it is supplied withthe cooling air, if directed normal to the drawing surface, whereby theradiation is effected from the bottom 50A of the radiating groove 50,too, to reduce the heat resistance of the semiconductor device.

[0413] Incidentally, in the structure of the present embodiment, themold resin 2A below the semiconductor chip 1 is thinned to make itnecessary to make a device when in the resin molding operation. If themold resin 2A having a low molten viscocity in the molding operation,the package 2 can be formed, as shown in FIG. 61.

[0414] Next, a modification of the resin-sealed type semiconductordevice of the foregoing Embodiment X is shown in FIG. 63 (presenting asection).

[0415] In this modified semiconductor device, as shown in FIG. 63, theupper surface of the package 2 shown in FIG. 61 is also formed with anopen radiating groove 53. The distance between the bottom 50A of theradiating groove 50 and the bottom 53A of the radiating groove 53, i.e.,the thickness of the mold resin below and above the semiconductor chip 1is set at 0.3 mm or less.

[0416] By thus thinning the mold resin 2A of the package 2 above thesemiconductor chip 1, the heat transfer surface is increased, but theheat resistance of the semiconductor device is decreased, so that thewhole heat resistance can be accordingly reduced. As shown in FIG. 69,moreover, the gap when the semiconductor device is mounted on thesubstrates 51A and 51B can be shortened by twice as large as the depthof the groove so that the packing density can be increased.

[0417] Another modification of the semiconductor device according to theEmbodiment X is shown in FIG. 64 or 65.

[0418] In this modified semiconductor device, as shown in FIG. 64 or 65,the mold resin 2A of the package of FIG. 62 or 63 below thesemiconductor chip 1 is removed to expose the side of the semiconductorchip 1, which is opposed to the principal surface, to the outside.

[0419] Thus, the mold resin 2A of the package 2 below the semiconductorchip 1 is removed to expose the side opposite to the principal surfaceof the semiconductor chip 1 to the outside so that the heat resistanceof the semiconductor device can be dropped to reduce the overall heatresistance accordingly.

[0420] Thus, it is possible to prevent the cracking from the cornerportions of the semiconductor chip 1 due to the temperature cycle.

[0421] Another modification of the semiconductor device of theEmbodiment X is shown in FIG. 66 or 67.

[0422] In this modified semiconductor device, as shown in FIG. 66 or 67,the relation between the semiconductor chip 1 and the output leads 3B isreversed in the semiconductor device in which the mold resin 2A of thepackage 2 shown in FIGS. 62 and 64 below the semiconductor chip 1 isremoved to expose the side of the semiconductor chip 1 opposite to theprincipal surface to the outside.

[0423] Thus, the cooling efficiency can be improved in case the coolingof the upper surface of the packing substrate 51 is dominant.

[0424] In the modification shown in FIG. 66 or 67, the the package 2 isfurther formed with the radiating groove at the side of the substrate.

[0425] Next, one embodiment of a method of packing the substrate of theresin-sealed type semiconductor device of the present invention shown inFIGS. 61 to 67 will be described in the following.

[0426] In the embodiment of the method of packing the substrate of theresin-sealed type semiconductor device shown in FIGS. 61 to 67, as shownin FIG. 68, the resin-sealed type semiconductor devices 60A to 60H shownin FIG. 61 are planarly packed on the respective two sides of thesubstrates 51A and 51B by means of solder 61.

[0427] By thus packing the resin-sealed type semiconductor devices 60Ato 60H on the substrates 51A and 51B, it is possible to improve thepacking density of the semiconductor device and to radiate from thesubstrates 51A and 51B of the package 2, too. More specifically, sincethe radiations of the resin-sealed type semiconductor devices 60A to 60Hare effected through the gap 51D between each of their packages 2 andthe substrate 51A or 51B packing the former, the resistance to thecooling draft can be reduced to improve the radiating efficiency.

[0428] As shown in FIG. 69, the radiating groove 53 and the rise 54above the package 2 of the resin-sealed type semiconductor device of theembodiment shown in FIG. 63 are packed together between the twosubstrates 51A and 51B.

[0429] Since the resin-sealed type semiconductor device is thus packed,its packing density can be further improved. The radiations can also beaccomplished from the side of the substrate 51A or 51B of the package 2.Specifically, the gap when the resin-sealed type semiconductor device isplaced over the substrate 51A or 51B can be shortened to one half of thedepth of the groove, the packing density can be increased (to 1.5 timesas high as that of the embodiment of FIG. 64).

[0430] Since, moreover, the radiations of the resin-sealed typesemicondutor device are accomplished through the gap 51D between thepackage 2 and its packing substrate 51A or 51B, the resistance to thecooling draft can be reduced to improve the radiating efficiency.

[Embodiment XI]

[0431] The resin-sealed type semiconductor device for sealing the DRAMaccording to the Embodiment XI of the present invention is shown in FIG.70 (presenting a perspective view showing the exterior) and FIG. 71(presenting a partially sectional view of FIG. 70).

[0432] As shown in FIGS. 70 and 71, the DRAM (or semiconductor chip) 1is sealed up with the ZIP (Zigzag In-line Package) type resin-sealedpackage 2. The DRAM 1 is constructed to have a large capacity of 16[Mbits]×1 [bit] and a rectangular shape of 16.48 [mm]×8.54 [mm]. ThisDRAM 1 is sealed in the resin-sealed type package 2 of 450 [mil].

[0433] The DRAM 1 has its principal surface arranged mainly with amemory cell array and a peripheral circuit, as shown in FIG. 71. Thememory cell array is arranged in a matrix form with memory cells (orelements) for storing information of 1 [bit], as will be described laterin detail. The peripheral circuit is composed of a direct peripheralcircuit and an indirect peripheral circuit. The direct peripheralcircuit is one for directly controlling the information writingoperations and the information reading operations of the memory cells.The direct peripheral circuit is exemplified by a row address decoder, acolumn address decoder or a sense amplifier. The indirect peripheralcircuit is one for controlling the operations of the direct peripheralcircuit indirectly. The indirect peripheral circuit is exemplified by aclock signal generator or a buffer.

[0434] The principal surface of the DRAM 1, i.e., the surface arrangedwith the memory cell array and the peripheral circuit is furtherarranged with the inner leads 3A. The insulating films 4 are sandwichedbetween the DRAM 1 and the inner leads 3A. The insulating films 4 aremade of a polyimide resin, for example. The surfaces of the insulatingfilms 4 at the individual sides of the DRAM 1 and the inner leads 3A areformed with adhesive layers. These adhesive layers are made of apolyester amide-imide resin or an epoxy resin. The package 2 of thiskind adopts the LOC (Lead On Chip) structure in which the inner leads 3Aare arranged over the DRAM 1. Since the package 2 adopting the LOCstructure can handle the inner leads 3A freely without being restrictedby the shape of the DRAM 1, it can seal the DRAM 1 having a sizeenlarged according to the free handling. In other words, the package 2adopting the LOC structure can have its packing density increasedbecause the sealing (or package) size can be suppressed to a small valueeven if the size of the DRAM 1 is enlarged with the large capacity.

[0435] The aforementioned inner leads 3A have their one-side ends madeintegral with the outer leads 3B. These outer leads 3B are regulatedwith signals to be applied and are numbered according to the standards.In FIGS. 70 and 71, the upper step is equipped sequentially from itsleft with terminals of odd numbers, e.g., 1st, 3rd, 5th, - - - , 21stand 23rd, and the lower step is equipped sequentially from its left withterminals of even numbers, e.g., 2nd, 4th, 6th, - - - , 22nd and 24th.In short, this package 2 is composed of totally twenty four terminals,i.e., the twelve terminals at each of the upper and lower steps.

[0436] The 1st one is an address signal terminal (A₉); The 2nd one is anidle terminal; the 3rd one is a column address strobe signal terminal({overscore (CAS)}); the 4th one is an idle terminal; the 5th one is adata output signal terminal; and the 6th one is a reference voltageV_(SS) terminal. This reference voltage V_(SS) is the circuit operationvoltage of 0 [V], for example. The 7th one is a power source voltageV_(CC) terminal. This power source voltage V_(CC) is the circuitoperation voltage of 5 [V], for example.

[0437] The 8th one is a data input signal terminal (D_(in)); the 9th oneis an idle terminal; the 10th one is a write enable signal terminal({overscore (WE)}); the 11th one is a row address strobe signal terminal({overscore (RAS)}); the 12th one is an address signal terminal (A₁₁);and the 13th one is an address signal terminal (A₁₀). The 14th one is anaddress signal terminal (A₀); the 15th one is an address signal terminal(A₁); the 16th one is an address signal terminal (A₂); the 17th one isan address signal terminal (A₂); and the 18th one is a power sourcevoltage V_(CC) terminal. This power source voltage V_(CC) is the circuitoperation voltage of 5 [V], for example.

[0438] The 19th one is a terminal for the reference voltage V_(SS),which is the circuit operation voltage of 0 [V], for example.

[0439] The 20th one is an address signal terminal (A₄); the 21th one isan address terminal (A₅); the 22th one is an address terminal (A₆); the23th one is an address terminal (A₇); and the 24th one is an addressterminal (A₈).

[0440] The other ends of the inner leads 3A are extended across theindividual longer sides of the rectangle of the DRAM 1 to the center ofthe DRAM 1. The extensions of the other ends of the inner leads 3A areconnected with the external terminals (i.e., bonding pads) BP arrayed atthe central portion of the DRAM 1 through the bonding wires 5. Thesebonding wires 5 are made of aluminum (Al) but may be coated wiresprepared by coating gold (Au), copper (Cu) or another metal wires withan insulating resin. The bonding wires 5 are bonded by the hot contactbonding method using ultrasonic vibrations.

[0441] Of the inner leads 3A, the inner leads (V_(CC)) 3A of the 7th and18th terminals are made integral and extended along the center portionof the DRAM 1 in parallel with the longer sides of the same (as will becalled the common inner leads or the bus bar inner leads). Likewise, theinner leads (V_(SS)) 3A of the 6th and 19th terminals are also madeintegral and extended along the center portion of the DRAM 1 in parallelwith the longer sides of the same (as will be called the common innerleads or the bus bar inner leads). The inner leads (V_(SS)) 3A areindividually extended in parallel in the regions which are defined bythe leading ends of the other ends of the remaining inner leads 3A. Eachof those inner leads (V_(CC)) 3A and (V_(SS)) 3A is enabled to supplythe power source voltage V_(CC) and the reference voltage V_(SS) to anyposition of the principal surface of the DRAM 1. In short, the package 2is constructed to absorb the power source noises easily thereby to speedup the operations of the DRAM 1.

[0442] The shorter sides of the rectangle of the DRAM 1 are equippedwith the chip supporting leads 3C.

[0443] Each of the inner leads 3A, the output leads 3B and the chipsupporting leads 3C is cut from the lead frame and is molded. This leadframe is made of a Fe—Ni alloy (containing 42 to 50 [%] of Ni) or Cu,for example.

[0444] The DRAM 1, the bonding wires 5, the inner leads 3A and the chipsupporting leads 3C are sealed up with the resin sealing portion 6. Thisresin sealing portion 6 is is made of an epoxy resin to which are addeda phenol hardener, silicon rubber and a filler so as to reduce thestress. The silicon rubber is effective to drop the modulus ofelasticity and the thermal expansion coefficient of the epoxy resin. Thefiller is formed in spherical grains of silicon oxide and is effectiveto drop the thermal expansion coefficient.

[0445] As is apparent from the description thus far made, according tothe present Embodiment XI, the 16M DRAM 1 of the ZIP package type ispacked in the vertical form in the substrate so that its packing densitycan be improved.

[0446] Although the present invention has been specifically described inconnection with the embodiments thereof, it should not be limitedthereto but can naturally be modified in various manners withoutdeparting from the gist thereof.

[0447] The effects to be obtained from the representatives of theinvention disclosed herein will be briefly enumerated in the following:

[0448] (1) The semiconductor device is enabled to improve thereliability;

[0449] (2) The semiconductor device is enabled to improve the signaltransmission rate and reduce the electrical noises by the stray capacitybetween the semiconductor chip and the leads;

[0450] (3) The semiconductor device is enabled to improve the radiationefficiency of the heat generated;

[0451] (4) The semiconductor device is enabled to reduce the influencesof the heat during the reflow;

[0452] (5) The semiconductor device is enabled to reduce the influencesof the heat in the temperature cycle;

[0453] (6) The semiconductor device is enabled to prevent the moldingdefect;

[0454] (7) The semiconductor device is enabled to improve theproductivity; and

[0455] (8) The semiconductor device is enabled to improve the moistureresistance

[Embodiment XII]

[0456]FIG. 72 is a section showing a semiconductor device according toanother embodiment of the present invention and taken along line XII-XIIof FIG. 74; FIG. 73 is a partially broken section taken along lineXIII-XIII of FIG. 74; FIG. 74 is a general top plan view showing thesemiconductor device; and FIG. 75 is a general top plan view showing thesemiconductor chip in a circuit block of the semiconductor device.

[0457] The present Embodiment XII is directed to the resin-sealed typesemiconductor device which has the DIP (Dual In-line Package) packagestructure using the tabless lead frame.

[0458] A package body 401 is made of a resin which is prepared byfilling an epoxy resin with a filler such as silica (SiC₂) to have athermal expansion coefficient near that of silicone and which has astructure strong against the bending and the reflow cracking.

[0459] From the longitudinal two sides of the package body 401, thereare extended to the outside and folded downward a plurality of leads 402which constitute input/output pins and power source pins. These leads402 are made of Cu, for example, and have their surfaces plated with aSn—Ni alloy, for example.

[0460] To the surfaces of the leads 402 buried in the package body 401,there are bonded through an adhesive 404 rectangular insulating films403 a which are made of a polyimide resin, for example. The adhesive 404is made of a polyimide resin, for example.

[0461] The leads 402 are folded, as shown in FIG. 74, below theInsulating films 403 a generally at a right angle in the horizontaldirection such that their leading end portions plated with Ag, forexample, extend from the shorter sides of the insulating films 403 a tothe outside.

[0462] As shown in FIGS. 72 and 73, moreover, the leads 402 are furtherfolded midway downward below the insulating films 403 a. To theresultant gaps between the leads 402 and the insulating films 403 a,there are adhered second insulating films 403 b which has asubstantially equal thickness, so as to prevent the leads 402 from beingdeformed when in the molding operation. Incidentally, the insulatingfilms 403 b are made of the same polyimide resin as that of theforegoing insulating film 403 a.

[0463] To the upper surfaces of the insulating films 403 a, there isbonded through an adhesive 406 a rectangular semiconductor chip 405which is made of single crystal of silicon. The adhesive 406 is made ofa silicon resin, for example.

[0464] The chip 405 is constructed to have a slightly smaller area thanthat of the insulating films 403 a. The chip 405 has its upper surfaceproviding an integrated circuit forming surface, which is covered with apassivation film 407 of a polyimide resin so that it may be flattend.

[0465] The integrated circuit forming surface of the chip 405 is formedwith a MOS DRAM of 4 mega bits, for example.

[0466] As shown in FIG. 75, the chip 405 is arranged at its center witha memory cell array M of the MOS DRAM of 4 mega bits and at its twosides with peripheral circuits P. Between the shorter sides of the chip405 and the peripheral circuits P, there are arranged a plurality ofbonding pads 408, which are electrically connected with the leads 402through wires 409 made of Au, Cu or Al.

[0467] In the resin-sealed semiconductor device, parasitic capacitiesare usually established between the chip 405 and the leads 402. Theseparasitic capacities will increase inversely proportinally to thedistance between the chip 405 and the leads 402 and proportionally totheir opposed areas. In the package structure in which most of the leads402 buried in the package body 401 are positioned below the chip 405,the opposed areas between the chip 405 and the leads 402 are enlarged toincrease the parasitic capacities.

[0468] In the present Embodiment XII, however, the leads 402 below thechip 405 are folded midway downward to enlarge the distance between thechip 405 and the leads 402. As a result, the parasitic capacities to beestablished between the chip 405 and the leads 402 can be reduced morethan the prior art in which the leads 402 are not folded midwaydownward.

[0469] As a result, the capacity of the leads 402 constituting theinput/output pins is reduced to speed up the access to the MOS DRAM of 4mega bits formed in the chip 405.

[0470] In the present Embodiment XII, the second insulating films 403 bmade of the same material as that of the insulating film 403 a areadhered to the gaps between the leads 402 and the insulating film 403a.However, the insulating films 403 a and 403 b may be molded in anintegral manner or made of different materials.

[Embodiment XIII]

[0471]FIG. 76 is a section showing a semiconductor device according toanother embodiment of the present invention and taken along line XIV-XIVof FIG. 77; FIG. 77 is a general top plan view showing the semiconductordevice; and FIG. 78 is a general top plan view showing the semiconductorchip of the circuit block of the semiconductor device.

[0472] The package structure of the present Embodiment XIII is the sameDIP of the tabless lead frame type at that of the foregoing EmbodimentXII. Although this Embodiment XII uses the so-called “Chip On Lead” typein which the leads 402 are arranged on the lower side of the chip 405,the present Embodiment XIII adopts the so-called Lead On Chip type inwhich the chip 405 is arranged on the lower side of the leads 402.

[0473] Specifically, the chip 405 sealed in the package body 401 made ofa resin similar to that of the foregoing Embodiment XII has its uppersurface providing an integrated circuit forming surface. This integratedcircuit forming surface is formed with a MOS DRAM of 4 mega bits, forexample.

[0474] As shown in FIG. 78, the chip 405 is arranged at its centralportion with the peripheral circuit P extending in the longitudinaldirection of the chip and at its two sides with the memory cell arraysM. Since the peripheral circuit P is arranged at the center of the chip405, the wiring length can be made less in the longitudinal direction ofthe chip 405 than that of the MOS DRAM of 4 mega bits of the EmbodimentXII, in which the peripheral circuits P are arranged at the shortersides of the chip 405, so that the wiring delay can be more reduced.

[0475] At the central portion of the chip 405, the bonding pads 408 areconcentrated between the peripheral circuit P and the memory cell arraysM.

[0476] To the upper surface of the chip 405, as shown in FIG. 76, thereis bonded through the adhesive 406 the rectangular insulating film 403 awhich is made of a polyimide resin, for example. This insulating film403 a has a slightly larger area than that of the chip 405 and is formedat its center with an opening 410.

[0477] To the upper surface of the insulating film 403 a, there arebonded through the adhesive 404 a plurality of leads 402. These leads402 are folded horizontally over the insulating film 403 a, as shown inFIG. 77, to have their leading end portions arranged in the vicinity ofthe bonding pads 408. Moreover, the leads 402 and the bonding pads 408are electrically connected through the wires 409.

[0478] As shown in FIG. 76, the leads 402 are folded midway upward overthe insulating film 403 a. To the resultant gaps between the leads 402and the insulating film 403 a, there are adhered the insulating films403 b which have substantially the same thickness as that of the gaps.

[0479] Thus, in the present Embodiment XIII, the leads 402 over the chip405 are folded midway upward to increase the distance between the chip405 and the leads 402 accordingly. As a result, the parasitic capacityto be formed between the chip 405 and the leads 402 can be reduced morethan the prior art in which the leads 402 are not folded midway upward.

[0480] As a result, the capacity of the leads 402 constituting theinput/output pins can be reduced to speed up the access to the MOS DRAMof 4 mega bits formed on the chip 405.

[0481] Although the invention has been specifically described inconnection with the embodiments thereof, it should not be limited to theEmbodiments XII and XIII but can naturally be modified in variousmanners within the gist thereof.

[0482] As shown in FIG. 79, for example, the present invention can beapplied to the package structure in which a predetermined integratedcircuit formed on the chip 405 and the leads 402 are electricallyconnected through solder bumps 411. In case, as shown, most of the leads402 buried in the package body 401 are arranged along the lower side ofthe chip 405, the parasitic capacity to be established between the leads402 and the chip 405 can be reduced by folding the intermediate portionsof the leads 402 connecting the solder bumps 411 downward.

[0483] Although the packages of the foregoing Embodiments XII and XIIIare of the DIP type, they should not be limited thereto but may beexemplified by the SOJ (Small Outline J-lead Package) or the PLCC(Plastic Leaded Chip Carrier).

[0484] Moreover, the present invention should not be limited to thesemiconductor device using the tabless lead frame type but can also beapplied to the semiconductor device of the type in which the leads arearranged on the upper surface of the chip packed on the tabs.

[0485] Although the description thus far made is directed to the case inwhich the invention is applied to the MOS RAM or the background of itsapplication, the invention should not be limited thereto but can beapplied to another semiconductor memory such as an EPROM or a logicalLSI such as a microcomputer.

[0486] The effects to be attained by the representative of the inventiondisclosed herein will be briefly described in the following:

[0487] Specifically, the parasitic capacity to be established betweenthe chip and the leads can be reduced by folding a portion of the leads,which are arranged over or below the chip packed in the package, outwardwith respect to the upper or lower sides of the chip.

[0488] Since, moreover, the insulating films are sandwiched between thechip and the leads, the distance between the chip and the leads can beso sufficiently enlarged to reduce the parasitic capacity to beestablished between the chip and the leads.

[0489] By arranging the peripheral circuit at the central portion of thechip, moreover, the wiring length taken in the longitudinal direction ofthe chip can be shortened to reduce the wiring delay. TABLE 1 ResinComposition (wt. parts) Base Resin: Embodiment 1: o-cresol novolak typeepoxy resin: 63 novolak type phenol resin: 37 Embodiment 2: resol typephenol resin: 80 o-cresol novolak type epoxy resin: 20 Embodiment 3:ether type bismaleimide resin: 70 epoxy acrylate resin: 30 HardeningCatalyzer: Embodiment 1: 1 triphenyl phosphine: Embodiment 2: 12-phenyl-4-metyl-5-hydromethyl imidazole: Embodiment 3: 0.5 dicumylperoxide: Fire Retardant: Embodiment 1: brominated bisphenol A-typeepoxy resin: 10 antimony trioxide: 5 Embodiment 2: Embodiment 3:brominated visphenol A-type epoxy resin: 8 antimony trioxide: 2Elasticizer: Embodiment 1: 10 modified epoxy silicone: Embodiment 2: 10modified amine silicone: Embodiment 3: 10 modified vinyl silicone:Filler Embodiment 1: 520 spherical molten silica: Embodiment 2: 460spherical molten silica: Embodiment 3: 520 spherical molten silica:Coupling Agent: Embodiment 1: 3 epoxy silane: Embodiment 2: 3 aminosilane: Embodiment 3: 3 amino silane: Parting Agent: Embodiment 1: 1montanic ester: Embodiment 2: 1 montanic ester: Embodiment 3: 1 montanicester: Coloring Agent: Embodiment 1: 1 carbon black Embodiment 2: 1carbon black Embodiment 3: 1 carbon black Molding Properties: MoltenViscosity (p) at 180° C.: Embodiment 1: 215 Embodiment 2: 150 Embodiment3: 200 Spiral Flow (inch): Embodiment 1: 35 Embodiment 2: 30 Embodiment3: 40 Hot Hardness at 180° C./90 s after: Embodiment 1: 85 Embodiment 2:85 Embodiment 3: 88 Physical Properties of Set Device: Glass TransitionTemperature (° C.) Embodiment 1: 165 Embodiment 2: 220 Embodiment 3: 215Linear Expansion Coefficient (10⁻⁵/° C.): Embodiment 1: 1.3 Embodiment2: 1.1 Embodiment 3: 1.1 Bending Strength (kgf/mm²) in Greenhouse:Embodiment 1: 13.5 Embodiment 2: 14.5 Embodiment 3: 13.2 at 215° C.:Embodiment 1: 1.2 Embodiment 2: 8.5 Embodiment 3: 5.5 Bulk Resistivity(ohms cm): in Greenhouse: Embodiment 1: 3.6 × 10¹⁶ Embodiment 2: 1.2 ×10¹⁶ Embodiment 3: 8.5 × 10¹⁶ at 140° C.: Embodiment 1: 4.0 × 10¹⁴Embodiment 2: 8.5 × 10¹³ Embodiment 3: 5.0 × 10¹⁵ Moisture Absorption(%) at 65° C./95% RH: Embodiment 1: 0.8 Embodiment 2: 0.8 Embodiment 3:1.0 Fire Retardance (UL-94, 1.6 mm thickness): Embodiment 1: V-OEmbodiment 2: V-O Embodiment 3: V-O Properties of Extract (120° C./afterextraction of 168 h): pH: Embodiment 1: 4.0 Embodiment 2: 4.2 Embodiment3: 4.0 Electrical Conductivity (μs/cm): Embodiment 1: 85 Embodiment 2:65 Embodiment 3: 150 CL⁻(ppm): Embodiment 1: 3.2 Embodiment 2: <1Embodiment 3: <1

[0490] TABLE 2 Washing Times 0 1 2 3 4 5 6 Properties of Extracts: pH3.0 3.3 3.4 3.4 3.5 3.5 3.6 Electrical 1500 350 125 50 27 20 18 (μs/cm)Conductivity Ionic Impurities (ppm) *1 CL⁻ 75 15 3 <1 <1 <1 <1 Br⁻ 5 <1<1 <1 <1 <1 <1 Na⁺ 30 8 2 <1 <1 <1 <1 K⁺ 15 3 <1 <1 <1 <1 <1 Zn⁺² 250 7518 3 <1 <1 <1 NH₄ ⁺ <1 <1 <1 <1 <1 <1 <1 Properties of Resins Softening62 65 65 68 70 73 75 Temp. (° C.) Gel Time 31 37 40 42 42 43 45 (sec) *2

What is claimed is:
 1. A semiconductor device comprising: asemiconductor chip having a main surface, said semiconductor chip havingan integrated circuit, external terminals on said main surface and apolyimide film covering said main surface, said polyimide film havingopenings exposing said external terminals, said main surface having apair of longer edges extending in a first direction and a pair ofshorter edges extending in a second direction which is different fromsaid first direction; first signal leads each having an inner lead andan outer lead which is continuous with said inner lead, each of theinner leads of said first signal leads crossing one of said pair oflonger edges and extending over said main surface, each of said innerleads of said first signal leads having a first portion which isdisposed over said main surface; second signal leads each having aninner lead and an outer lead which is continuous with said inner lead,each of said inner leads of said second signal leads crossing the otherof said pair of longer edges and extending over said main surface, eachof said inner leads of said second signal leads having a first portionwhich is disposed over said main surface; a first insulating adhesivelayer being disposed between said polyimide film and said first portionsof said first signal leads, said first insulating adhesive layerincluding a base insulating film and adhesive formed on both sides ofsaid base insulating film, said first signal leads being fixed to saidsemiconductor chip via said first insulating adhesive layer; a secondinsulating adhesive layer being disposed between said polyimide film andsaid first portions of said second signal leads, said second insulatingadhesive layer including a base insulating film and adhesive formed onboth sides of said base insulating film, said second signal leads beingfixed to said semiconductor chip via said second insulating adhesivelayer; bonding wires electrically connecting said external terminalswith said first portions of said first and second signal leadsrespectively; and a resin member having a pair of longer sides extendingin said first direction and a pair of shorter sides extending in saidsecond direction, said resin member sealing said semiconductor chip,said inner leads of said first signal leads protruding outwardly fromone of a pair of longer sides adjacent to said one of the longer edgesof said main surface of said semiconductor chip, said outer leads ofsaid second signal leads protruding outwardly from the other of saidpair of longer sides adjacent to the other of the longer edges of saidmain surface of said semiconductor chip, wherein said first and secondinsulating adhesive layers are discontinuous with each other in saidsecond direction.
 2. A semiconductor device according to claim 1 ,wherein said base insulating film of each of said first and secondinsulating adhesive layers includes a thermoplastic resin.
 3. Asemiconductor device according to claim 2 , wherein said thermoplasticresin includes a polyimide resin.
 4. A semiconductor device according toclaim 3 , wherein said adhesive on the both sides of said baseinsulating film includes a polyamide-imide resin.
 5. A semiconductordevice according to claim 1 , wherein said external terminals extend insaid first direction and are arranged at a substantially centralposition between said pair of longer edges.
 6. A semiconductor deviceaccording to claim 5 , wherein said first insulating adhesive layer isdisposed between said external terminals and said one of said pair oflonger edges in a plane view, and wherein said second insulatingadhesive layer is disposed between said external terminals and the otherof said pair of longer edges in said plane view.
 7. A semiconductordevice according to claim 6 , wherein said polyimide film iscontinuously formed on said main surface of said semiconductor chipexcept for regions where said external terminals are formed.
 8. Asemiconductor device according to claim 1 , wherein said integratedcircuit of said semiconductor chip includes a memory circuit.
 9. Asemiconductor device according to claim 8 , wherein said polyimide filmacts as a shield against an alpha-ray.
 10. A semiconductor deviceaccording to claim 9 , wherein said polyimide film has a thickness of2.0 to 10.0 microns.
 11. A semiconductor device according to claim 2 ,wherein said resin member includes a thermosetting resin.
 12. Asemiconductor device according to claim 1 , wherein each of said innerleads of said first and second signal leads has the first portion, asecond portion and a stepped portion between said first and secondportions, wherein said second portion is farther than said first portionfrom said main surface in a thickness direction of said semiconductorchip, and is spaced from said polyimide film, and wherein said first andsecond insulating adhesive layers are disposed between said polyimidefilm and said first portion of each of said first and second signalleads respectively.
 13. A semiconductor device according to claim 12 ,wherein said first portions of said first and second signal leadscorrespond to areas where said bonding wires are bonded.
 14. Asemiconductor device according to claim 1 , wherein the main surface ofthe semiconductor chip has a rectangular shape, and the resin member hasa rectangular shape.
 15. A semiconductor device comprising: asemiconductor chip having a main surface, said semiconductor chip havingan integrated circuit, external terminals formed on said main surfaceand an alpha-ray shielding film formed to cover said main surface, saidalpha-ray shielding film having openings exposing said externalterminals, said main surface having a pair of longer edges extending ina first direction and a pair of shorter edges extending in a seconddirection which is different from said first direction; first signalleads each having an inner lead and an outer lead which is continuouswith said inner lead, each of said inner leads of said first signalleads crossing one of said pair of longer edges and extending over saidmain surface, each of said inner leads of said first signal leads havinga first portion which is disposed over said main surface; second signalleads each having an inner lead and an outer lead which is continuouswith said inner lead, each of said inner leads of said second signalleads crossing over said main surface, each of said inner leads of saidsecond signal leads having a first portion which is disposed over saidmain surface; a first insulating adhesive layer being disposed betweensaid alpha-ray shielding film and said first portions of said firstsignal leads, said first insulating adhesive layer including a baseinsulating film and adhesive formed on both sides of said baseinsulating film, said first signal leads being fixed to saidsemiconductor chip via said first insulating adhesive layer; a secondinsulating adhesive layer being disposed between said alpha-rayshielding film and said first portions of said second signal leads, saidsecond insulating adhesive layer including a base insulating film andadhesive formed on both sides of said base insulating film, said secondsignal leads being fixed to said semiconductor chip via said secondinsulating adhesive layer; bonding wires electrically connecting saidexternal terminals with said first portions of said first and secondsignal leads respectively; and a resin member having a pair of longersides extending in said first direction and a pair of shorter sidesextending in said second direction, said resin member sealing saidsemiconductor chip, said inner leads of said first signal leadsprotruding outwardly from one of a pair of longer sides adjacent to saidone of the longer edges of said main surface of said semiconductor chip,said outer leads of said second signal leads protruding outwardly fromthe other of said pair of longer sides adjacent to the other of thelonger edges of said main surface of said semiconductor chip, whereinsaid first and second insulating adhesive layers are discontinuous witheach other in said second direction.
 16. A semiconductor deviceaccording to claim 15 , wherein said base insulating film of each ofsaid first and second insulating adhesive layers includes athermoplastic resin.
 17. A semiconductor device according to claim 16 ,wherein said thermoplastic resin includes a polyimide resin.
 18. Asemiconductor device according to claim 17 , wherein said adhesive onthe both sides of said base insulating film includes a polyamide-imideresin.
 19. A semiconductor device according to claim 15 , wherein saidexternal terminals extend in said first direction and are arranged at asubstantially central position between said pair of longer edges.
 20. Asemiconductor device according to claim 19 , wherein said firstinsulating adhesive layer is disposed between said external terminalsand said one of said pair of longer edges in a plane view, and whereinsaid second insulating adhesive layer is disposed between said externalterminals and the other of said pair of longer edges in said plane view.21. A semiconductor device according to claim 20 , wherein saidalpha-ray shielding film is continuously formed on said main surface ofsaid semiconductor chip except for regions where said external terminalsare formed.
 22. A semiconductor device according to claim 15 , whereinsaid integrated circuit of said semiconductor chip includes a memorycircuit.
 23. A semiconductor device according to claim 22 , wherein saidalpha-ray shielding film acts as a shield against an alpha-ray.
 24. Asemiconductor device according to claim 23 , wherein said alpha-rayshielding film has a thickness of 2.0 to 10.0 microns.
 25. Asemiconductor device according to claim 16 , wherein said resin memberincludes a thermosetting resin.
 26. A semiconductor device according toclaim 15 , wherein each of said inner leads of said first and secondsignal leads has the first portion, a second portion and a steppedportion between said first and second portions, wherein said secondportion is farther than said first portion from said main surface in athickness direction of said semiconductor chip, and is spaced from saidalpha-ray shielding film, and wherein said first and second insulatingadhesive layers are disposed between said alpha-ray shielding film andsaid first portion of each of said first and second signal leadsrespectively.
 27. A semiconductor device according to claim 26 , whereinsaid first portions of said first and second signal leads correspond toareas where said bonding wires are bonded.
 28. A semiconductor deviceaccording to claim 15 , wherein the main surface of the semiconductorchip has a rectangular shape, and the resin member has a rectangularshape.